diff --git a/examples/scripts/data_dependency.py b/examples/scripts/data_dependency.py
index 478394766..23c82cae1 100644
--- a/examples/scripts/data_dependency.py
+++ b/examples/scripts/data_dependency.py
@@ -18,6 +18,8 @@ assert len(contracts) == 1
 contract = contracts[0]
 destination = contract.get_state_variable_from_name("destination")
 source = contract.get_state_variable_from_name("source")
+assert source
+assert destination
 
 print(f"{source} is dependent of {destination}: {is_dependent(source, destination, contract)}")
 assert not is_dependent(source, destination, contract)
@@ -47,9 +49,11 @@ print(f"{destination} is tainted {is_tainted(destination, contract)}")
 assert is_tainted(destination, contract)
 
 destination_indirect_1 = contract.get_state_variable_from_name("destination_indirect_1")
+assert destination_indirect_1
 print(f"{destination_indirect_1} is tainted {is_tainted(destination_indirect_1, contract)}")
 assert is_tainted(destination_indirect_1, contract)
 destination_indirect_2 = contract.get_state_variable_from_name("destination_indirect_2")
+assert destination_indirect_2
 print(f"{destination_indirect_2} is tainted {is_tainted(destination_indirect_2, contract)}")
 assert is_tainted(destination_indirect_2, contract)
 
@@ -88,6 +92,8 @@ contract = contracts[0]
 contract_derived = slither.get_contract_from_name("Derived")[0]
 destination = contract.get_state_variable_from_name("destination")
 source = contract.get_state_variable_from_name("source")
+assert destination
+assert source
 
 print(f"{destination} is dependent of {source}: {is_dependent(destination, source, contract)}")
 assert not is_dependent(destination, source, contract)
diff --git a/examples/scripts/variable_in_condition.py b/examples/scripts/variable_in_condition.py
index 43dcf41e7..bde41424d 100644
--- a/examples/scripts/variable_in_condition.py
+++ b/examples/scripts/variable_in_condition.py
@@ -14,6 +14,7 @@ assert len(contracts) == 1
 contract = contracts[0]
 # Get the variable
 var_a = contract.get_state_variable_from_name("a")
+assert var_a
 
 # Get the functions reading the variable
 functions_reading_a = contract.get_functions_reading_from_variable(var_a)
diff --git a/slither/__main__.py b/slither/__main__.py
index a5d51dcd6..d6c3ea717 100644
--- a/slither/__main__.py
+++ b/slither/__main__.py
@@ -615,7 +615,9 @@ def parse_args(
 
 
 class ListDetectors(argparse.Action):  # pylint: disable=too-few-public-methods
-    def __call__(self, parser, *args, **kwargs):  # pylint: disable=signature-differs
+    def __call__(
+        self, parser: Any, *args: Any, **kwargs: Any
+    ) -> None:  # pylint: disable=signature-differs
         detectors, _ = get_detectors_and_printers()
         output_detectors(detectors)
         parser.exit()
diff --git a/slither/analyses/data_dependency/data_dependency.py b/slither/analyses/data_dependency/data_dependency.py
index 2b66f2bb3..d133cd2dc 100644
--- a/slither/analyses/data_dependency/data_dependency.py
+++ b/slither/analyses/data_dependency/data_dependency.py
@@ -2,7 +2,7 @@
     Compute the data depenency between all the SSA variables
 """
 from collections import defaultdict
-from typing import Union, Set, Dict, TYPE_CHECKING
+from typing import Union, Set, Dict, TYPE_CHECKING, List
 
 from slither.core.cfg.node import Node
 from slither.core.declarations import (
@@ -20,6 +20,7 @@ from slither.core.solidity_types.type import Type
 from slither.core.variables.top_level_variable import TopLevelVariable
 from slither.core.variables.variable import Variable
 from slither.slithir.operations import Index, OperationWithLValue, InternalCall, Operation
+from slither.slithir.utils.utils import LVALUE
 from slither.slithir.variables import (
     Constant,
     LocalIRVariable,
@@ -29,6 +30,7 @@ from slither.slithir.variables import (
     TemporaryVariableSSA,
     TupleVariableSSA,
 )
+from slither.slithir.variables.variable import SlithIRVariable
 
 if TYPE_CHECKING:
     from slither.core.compilation_unit import SlitherCompilationUnit
@@ -393,13 +395,9 @@ def transitive_close_dependencies(
     while changed:
         changed = False
         to_add = defaultdict(set)
-        [  # pylint: disable=expression-not-assigned
-            [
+        for key, items in context.context[context_key].items():
+            for item in items & keys:
                 to_add[key].update(context.context[context_key][item] - {key} - items)
-                for item in items & keys
-            ]
-            for key, items in context.context[context_key].items()
-        ]
         for k, v in to_add.items():
             # Because we dont have any check on the update operation
             # We might update an empty set with an empty set
@@ -418,20 +416,20 @@ def add_dependency(lvalue: Variable, function: Function, ir: Operation, is_prote
         function.context[KEY_SSA][lvalue] = set()
         if not is_protected:
             function.context[KEY_SSA_UNPROTECTED][lvalue] = set()
+    read: Union[List[Union[LVALUE, SolidityVariableComposed]], List[SlithIRVariable]]
     if isinstance(ir, Index):
         read = [ir.variable_left]
-    elif isinstance(ir, InternalCall):
+    elif isinstance(ir, InternalCall) and ir.function:
         read = ir.function.return_values_ssa
     else:
         read = ir.read
-    # pylint: disable=expression-not-assigned
-    [function.context[KEY_SSA][lvalue].add(v) for v in read if not isinstance(v, Constant)]
+    for v in read:
+        if not isinstance(v, Constant):
+            function.context[KEY_SSA][lvalue].add(v)
     if not is_protected:
-        [
-            function.context[KEY_SSA_UNPROTECTED][lvalue].add(v)
-            for v in read
-            if not isinstance(v, Constant)
-        ]
+        for v in read:
+            if not isinstance(v, Constant):
+                function.context[KEY_SSA_UNPROTECTED][lvalue].add(v)
 
 
 def compute_dependency_function(function: Function) -> None:
diff --git a/slither/core/declarations/contract.py b/slither/core/declarations/contract.py
index 38b4221d9..2c82f9b58 100644
--- a/slither/core/declarations/contract.py
+++ b/slither/core/declarations/contract.py
@@ -49,6 +49,9 @@ if TYPE_CHECKING:
 
 LOGGER = logging.getLogger("Contract")
 
+USING_FOR_KEY = Union[str, Type]
+USING_FOR_ITEM = List[Union[Type, Function]]
+
 
 class Contract(SourceMapping):  # pylint: disable=too-many-public-methods
     """
@@ -80,8 +83,8 @@ class Contract(SourceMapping):  # pylint: disable=too-many-public-methods
         self._custom_errors: Dict[str, "CustomErrorContract"] = {}
 
         # The only str is "*"
-        self._using_for: Dict[Union[str, Type], List[Type]] = {}
-        self._using_for_complete: Optional[Dict[Union[str, Type], List[Type]]] = None
+        self._using_for: Dict[USING_FOR_KEY, USING_FOR_ITEM] = {}
+        self._using_for_complete: Optional[Dict[USING_FOR_KEY, USING_FOR_ITEM]] = None
         self._kind: Optional[str] = None
         self._is_interface: bool = False
         self._is_library: bool = False
@@ -123,7 +126,7 @@ class Contract(SourceMapping):  # pylint: disable=too-many-public-methods
         return self._name
 
     @name.setter
-    def name(self, name: str):
+    def name(self, name: str) -> None:
         self._name = name
 
     @property
@@ -133,7 +136,7 @@ class Contract(SourceMapping):  # pylint: disable=too-many-public-methods
         return self._id
 
     @id.setter
-    def id(self, new_id):
+    def id(self, new_id: int) -> None:
         """Unique id."""
         self._id = new_id
 
@@ -146,7 +149,7 @@ class Contract(SourceMapping):  # pylint: disable=too-many-public-methods
         return self._kind
 
     @contract_kind.setter
-    def contract_kind(self, kind):
+    def contract_kind(self, kind: str) -> None:
         self._kind = kind
 
     @property
@@ -154,7 +157,7 @@ class Contract(SourceMapping):  # pylint: disable=too-many-public-methods
         return self._is_interface
 
     @is_interface.setter
-    def is_interface(self, is_interface: bool):
+    def is_interface(self, is_interface: bool) -> None:
         self._is_interface = is_interface
 
     @property
@@ -162,7 +165,7 @@ class Contract(SourceMapping):  # pylint: disable=too-many-public-methods
         return self._is_library
 
     @is_library.setter
-    def is_library(self, is_library: bool):
+    def is_library(self, is_library: bool) -> None:
         self._is_library = is_library
 
     # endregion
@@ -266,16 +269,18 @@ class Contract(SourceMapping):  # pylint: disable=too-many-public-methods
     ###################################################################################
 
     @property
-    def using_for(self) -> Dict[Union[str, Type], List[Type]]:
+    def using_for(self) -> Dict[USING_FOR_KEY, USING_FOR_ITEM]:
         return self._using_for
 
     @property
-    def using_for_complete(self) -> Dict[Union[str, Type], List[Type]]:
+    def using_for_complete(self) -> Dict[USING_FOR_KEY, USING_FOR_ITEM]:
         """
         Dict[Union[str, Type], List[Type]]: Dict of merged local using for directive with top level directive
         """
 
-        def _merge_using_for(uf1: Dict, uf2: Dict) -> Dict:
+        def _merge_using_for(
+            uf1: Dict[USING_FOR_KEY, USING_FOR_ITEM], uf2: Dict[USING_FOR_KEY, USING_FOR_ITEM]
+        ) -> Dict[USING_FOR_KEY, USING_FOR_ITEM]:
             result = {**uf1, **uf2}
             for key, value in result.items():
                 if key in uf1 and key in uf2:
@@ -1452,7 +1457,7 @@ class Contract(SourceMapping):  # pylint: disable=too-many-public-methods
             result = func.get_last_ssa_state_variables_instances()
             for variable_name, instances in result.items():
                 # TODO: investigate the next operation
-                last_state_variables_instances[variable_name] += instances
+                last_state_variables_instances[variable_name] += list(instances)
 
         for func in self.functions + list(self.modifiers):
             func.fix_phi(last_state_variables_instances, initial_state_variables_instances)
diff --git a/slither/core/declarations/custom_error.py b/slither/core/declarations/custom_error.py
index c566fccec..7e78748c6 100644
--- a/slither/core/declarations/custom_error.py
+++ b/slither/core/declarations/custom_error.py
@@ -1,4 +1,4 @@
-from typing import List, TYPE_CHECKING, Optional, Type, Union
+from typing import List, TYPE_CHECKING, Optional, Type
 
 from slither.core.solidity_types import UserDefinedType
 from slither.core.source_mapping.source_mapping import SourceMapping
@@ -42,7 +42,7 @@ class CustomError(SourceMapping):
     ###################################################################################
 
     @staticmethod
-    def _convert_type_for_solidity_signature(t: Optional[Union[Type, List[Type]]]) -> str:
+    def _convert_type_for_solidity_signature(t: Optional[Type]) -> str:
         # pylint: disable=import-outside-toplevel
         from slither.core.declarations import Contract
 
@@ -72,7 +72,7 @@ class CustomError(SourceMapping):
         Returns:
 
         """
-        parameters = [x.type for x in self.parameters]
+        parameters = [x.type for x in self.parameters if x.type]
         self._full_name = self.name + "(" + ",".join(map(str, parameters)) + ")"
         solidity_parameters = map(self._convert_type_for_solidity_signature, parameters)
         self._solidity_signature = self.name + "(" + ",".join(solidity_parameters) + ")"
diff --git a/slither/core/declarations/using_for_top_level.py b/slither/core/declarations/using_for_top_level.py
index 27d1f90e4..edf846a5b 100644
--- a/slither/core/declarations/using_for_top_level.py
+++ b/slither/core/declarations/using_for_top_level.py
@@ -1,5 +1,6 @@
 from typing import TYPE_CHECKING, List, Dict, Union
 
+from slither.core.declarations.contract import USING_FOR_KEY, USING_FOR_ITEM
 from slither.core.solidity_types.type import Type
 from slither.core.declarations.top_level import TopLevel
 
@@ -14,5 +15,5 @@ class UsingForTopLevel(TopLevel):
         self.file_scope: "FileScope" = scope
 
     @property
-    def using_for(self) -> Dict[Union[str, Type], List[Type]]:
+    def using_for(self) -> Dict[USING_FOR_KEY, USING_FOR_ITEM]:
         return self._using_for
diff --git a/slither/core/variables/variable.py b/slither/core/variables/variable.py
index 0d610c928..2b777e672 100644
--- a/slither/core/variables/variable.py
+++ b/slither/core/variables/variable.py
@@ -160,8 +160,8 @@ class Variable(SourceMapping):
 
         return (
             self.name,
-            [str(x) for x in export_nested_types_from_variable(self)],
-            [str(x) for x in export_return_type_from_variable(self)],
+            [str(x) for x in export_nested_types_from_variable(self)],  # type: ignore
+            [str(x) for x in export_return_type_from_variable(self)],  # type: ignore
         )
 
     @property
@@ -179,4 +179,5 @@ class Variable(SourceMapping):
         return f'{name}({",".join(parameters)})'
 
     def __str__(self) -> str:
+        assert self._name
         return self._name
diff --git a/slither/detectors/statements/costly_operations_in_loop.py b/slither/detectors/statements/costly_operations_in_loop.py
index 6af04329c..53fa12647 100644
--- a/slither/detectors/statements/costly_operations_in_loop.py
+++ b/slither/detectors/statements/costly_operations_in_loop.py
@@ -43,7 +43,7 @@ def costly_operations_in_loop(
             if isinstance(ir, OperationWithLValue) and isinstance(ir.lvalue, StateVariable):
                 ret.append(ir.node)
                 break
-            if isinstance(ir, (InternalCall)):
+            if isinstance(ir, (InternalCall)) and ir.function:
                 costly_operations_in_loop(ir.function.entry_point, in_loop_counter, visited, ret)
 
     for son in node.sons:
diff --git a/slither/detectors/statements/write_after_write.py b/slither/detectors/statements/write_after_write.py
index 40a82d3ff..1f11921cb 100644
--- a/slither/detectors/statements/write_after_write.py
+++ b/slither/detectors/statements/write_after_write.py
@@ -37,6 +37,8 @@ def _handle_ir(
         _remove_states(written)
 
     if isinstance(ir, InternalCall):
+        if not ir.function:
+            return
         if ir.function.all_high_level_calls() or ir.function.all_library_calls():
             _remove_states(written)
 
diff --git a/slither/printers/call/call_graph.py b/slither/printers/call/call_graph.py
index 0a4df0c65..38225e6d7 100644
--- a/slither/printers/call/call_graph.py
+++ b/slither/printers/call/call_graph.py
@@ -13,6 +13,7 @@ from slither.core.declarations.function import Function
 from slither.core.declarations.solidity_variables import SolidityFunction
 from slither.core.variables.variable import Variable
 from slither.printers.abstract_printer import AbstractPrinter
+from slither.utils.output import Output
 
 
 def _contract_subgraph(contract: Contract) -> str:
@@ -222,7 +223,7 @@ class PrinterCallGraph(AbstractPrinter):
 
     WIKI = "https://github.com/trailofbits/slither/wiki/Printer-documentation#call-graph"
 
-    def output(self, filename):
+    def output(self, filename: str) -> Output:
         """
         Output the graph in filename
         Args:
diff --git a/slither/printers/summary/constructor_calls.py b/slither/printers/summary/constructor_calls.py
index 665c76546..789811c36 100644
--- a/slither/printers/summary/constructor_calls.py
+++ b/slither/printers/summary/constructor_calls.py
@@ -5,6 +5,7 @@ from slither.core.declarations import Function
 from slither.core.source_mapping.source_mapping import Source
 from slither.printers.abstract_printer import AbstractPrinter
 from slither.utils import output
+from slither.utils.output import Output
 
 
 def _get_source_code(cst: Function) -> str:
@@ -17,7 +18,7 @@ class ConstructorPrinter(AbstractPrinter):
     ARGUMENT = "constructor-calls"
     HELP = "Print the constructors executed"
 
-    def output(self, _filename):
+    def output(self, _filename: str) -> Output:
         info = ""
         for contract in self.slither.contracts_derived:
             stack_name = []
diff --git a/slither/printers/summary/contract.py b/slither/printers/summary/contract.py
index 5af953e20..5fee94416 100644
--- a/slither/printers/summary/contract.py
+++ b/slither/printers/summary/contract.py
@@ -2,9 +2,13 @@
     Module printing summary of the contract
 """
 import collections
+from typing import Dict, List
+
+from slither.core.declarations import FunctionContract
 from slither.printers.abstract_printer import AbstractPrinter
 from slither.utils import output
 from slither.utils.colors import blue, green, magenta
+from slither.utils.output import Output
 
 
 class ContractSummary(AbstractPrinter):
@@ -13,7 +17,7 @@ class ContractSummary(AbstractPrinter):
 
     WIKI = "https://github.com/trailofbits/slither/wiki/Printer-documentation#contract-summary"
 
-    def output(self, _filename):  # pylint: disable=too-many-locals
+    def output(self, _filename: str) -> Output:  # pylint: disable=too-many-locals
         """
         _filename is not used
         Args:
@@ -53,17 +57,16 @@ class ContractSummary(AbstractPrinter):
 
             # Order the function with
             # contract_declarer -> list_functions
-            public = [
+            public_function = [
                 (f.contract_declarer.name, f)
                 for f in c.functions
                 if (not f.is_shadowed and not f.is_constructor_variables)
             ]
-            collect = collections.defaultdict(list)
-            for a, b in public:
+            collect: Dict[str, List[FunctionContract]] = collections.defaultdict(list)
+            for a, b in public_function:
                 collect[a].append(b)
-            public = list(collect.items())
 
-            for contract, functions in public:
+            for contract, functions in collect.items():
                 txt += blue(f"  - From {contract}\n")
 
                 functions = sorted(functions, key=lambda f: f.full_name)
@@ -90,7 +93,7 @@ class ContractSummary(AbstractPrinter):
         self.info(txt)
 
         res = self.generate_output(txt)
-        for contract, additional_fields in all_contracts:
-            res.add(contract, additional_fields=additional_fields)
+        for current_contract, current_additional_fields in all_contracts:
+            res.add(current_contract, additional_fields=current_additional_fields)
 
         return res
diff --git a/slither/printers/summary/variable_order.py b/slither/printers/summary/variable_order.py
index 9dc9e77c2..3325b7a01 100644
--- a/slither/printers/summary/variable_order.py
+++ b/slither/printers/summary/variable_order.py
@@ -4,6 +4,7 @@
 
 from slither.printers.abstract_printer import AbstractPrinter
 from slither.utils.myprettytable import MyPrettyTable
+from slither.utils.output import Output
 
 
 class VariableOrder(AbstractPrinter):
@@ -13,7 +14,7 @@ class VariableOrder(AbstractPrinter):
 
     WIKI = "https://github.com/trailofbits/slither/wiki/Printer-documentation#variable-order"
 
-    def output(self, _filename):
+    def output(self, _filename: str) -> Output:
         """
         _filename is not used
         Args:
diff --git a/slither/slithir/utils/ssa.py b/slither/slithir/utils/ssa.py
index 8b16cd516..9a180d14f 100644
--- a/slither/slithir/utils/ssa.py
+++ b/slither/slithir/utils/ssa.py
@@ -366,7 +366,7 @@ def last_name(
 
 def is_used_later(
     initial_node: Node,
-    variable: Union[StateIRVariable, LocalVariable],
+    variable: Union[StateIRVariable, LocalVariable, TemporaryVariableSSA],
 ) -> bool:
     # TODO: does not handle the case where its read and written in the declaration node
     # It can be problematic if this happens in a loop/if structure
diff --git a/slither/slithir/utils/utils.py b/slither/slithir/utils/utils.py
index a0ca0bd6f..4619c08bc 100644
--- a/slither/slithir/utils/utils.py
+++ b/slither/slithir/utils/utils.py
@@ -46,7 +46,7 @@ def is_valid_rvalue(v: SourceMapping) -> bool:
     )
 
 
-def is_valid_lvalue(v) -> bool:
+def is_valid_lvalue(v: SourceMapping) -> bool:
     return isinstance(
         v,
         (
diff --git a/slither/slithir/variables/local_variable.py b/slither/slithir/variables/local_variable.py
index eb32d4024..35b624a01 100644
--- a/slither/slithir/variables/local_variable.py
+++ b/slither/slithir/variables/local_variable.py
@@ -41,11 +41,11 @@ class LocalIRVariable(
             self._non_ssa_version = local_variable
 
     @property
-    def index(self):
+    def index(self) -> int:
         return self._index
 
     @index.setter
-    def index(self, idx):
+    def index(self, idx: int) -> None:
         self._index = idx
 
     @property
diff --git a/slither/slithir/variables/state_variable.py b/slither/slithir/variables/state_variable.py
index 7bb3a4077..f7fb8ab8a 100644
--- a/slither/slithir/variables/state_variable.py
+++ b/slither/slithir/variables/state_variable.py
@@ -30,11 +30,11 @@ class StateIRVariable(
             self._non_ssa_version = state_variable
 
     @property
-    def index(self):
+    def index(self) -> int:
         return self._index
 
     @index.setter
-    def index(self, idx):
+    def index(self, idx: int) -> None:
         self._index = idx
 
     @property
diff --git a/slither/slithir/variables/variable.py b/slither/slithir/variables/variable.py
index a1a1a6df9..20d203ea4 100644
--- a/slither/slithir/variables/variable.py
+++ b/slither/slithir/variables/variable.py
@@ -7,8 +7,9 @@ class SlithIRVariable(Variable):
         self._index = 0
 
     @property
-    def ssa_name(self):
+    def ssa_name(self) -> str:
+        assert self.name
         return self.name
 
-    def __str__(self):
+    def __str__(self) -> str:
         return self.ssa_name
diff --git a/slither/solc_parsing/declarations/contract.py b/slither/solc_parsing/declarations/contract.py
index 47ee7ec10..b9dbe9a9f 100644
--- a/slither/solc_parsing/declarations/contract.py
+++ b/slither/solc_parsing/declarations/contract.py
@@ -1,6 +1,6 @@
 import logging
 import re
-from typing import Any, List, Dict, Callable, TYPE_CHECKING, Union, Set
+from typing import Any, List, Dict, Callable, TYPE_CHECKING, Union, Set, Sequence
 
 from slither.core.declarations import (
     Modifier,
@@ -9,10 +9,10 @@ from slither.core.declarations import (
     StructureContract,
     Function,
 )
-from slither.core.declarations.contract import Contract
+from slither.core.declarations.contract import Contract, USING_FOR_KEY
 from slither.core.declarations.custom_error_contract import CustomErrorContract
 from slither.core.declarations.function_contract import FunctionContract
-from slither.core.solidity_types import ElementaryType, TypeAliasContract, Type
+from slither.core.solidity_types import ElementaryType, TypeAliasContract
 from slither.core.variables.state_variable import StateVariable
 from slither.solc_parsing.declarations.caller_context import CallerContextExpression
 from slither.solc_parsing.declarations.custom_error import CustomErrorSolc
@@ -302,7 +302,7 @@ class ContractSolc(CallerContextExpression):
         st.set_contract(self._contract)
         st.set_offset(struct["src"], self._contract.compilation_unit)
 
-        st_parser = StructureContractSolc(st, struct, self)
+        st_parser = StructureContractSolc(st, struct, self)  # type: ignore
         self._contract.structures_as_dict[st.name] = st
         self._structures_parser.append(st_parser)
 
@@ -312,7 +312,7 @@ class ContractSolc(CallerContextExpression):
 
         for struct in self._structuresNotParsed:
             self._parse_struct(struct)
-        self._structuresNotParsed = None
+        self._structuresNotParsed = []
 
     def _parse_custom_error(self, custom_error: Dict) -> None:
         ce = CustomErrorContract(self.compilation_unit)
@@ -329,7 +329,7 @@ class ContractSolc(CallerContextExpression):
 
         for custom_error in self._customErrorParsed:
             self._parse_custom_error(custom_error)
-        self._customErrorParsed = None
+        self._customErrorParsed = []
 
     def parse_state_variables(self) -> None:
         for father in self._contract.inheritance_reverse:
@@ -356,6 +356,7 @@ class ContractSolc(CallerContextExpression):
             var_parser = StateVariableSolc(var, varNotParsed)
             self._variables_parser.append(var_parser)
 
+            assert var.name
             self._contract.variables_as_dict[var.name] = var
             self._contract.add_variables_ordered([var])
 
@@ -365,7 +366,7 @@ class ContractSolc(CallerContextExpression):
         modif.set_contract(self._contract)
         modif.set_contract_declarer(self._contract)
 
-        modif_parser = ModifierSolc(modif, modifier_data, self, self.slither_parser)
+        modif_parser = ModifierSolc(modif, modifier_data, self, self.slither_parser)  # type: ignore
         self._contract.compilation_unit.add_modifier(modif)
         self._modifiers_no_params.append(modif_parser)
         self._modifiers_parser.append(modif_parser)
@@ -375,7 +376,7 @@ class ContractSolc(CallerContextExpression):
     def parse_modifiers(self) -> None:
         for modifier in self._modifiersNotParsed:
             self._parse_modifier(modifier)
-        self._modifiersNotParsed = None
+        self._modifiersNotParsed = []
 
     def _parse_function(self, function_data: Dict) -> None:
         func = FunctionContract(self._contract.compilation_unit)
@@ -383,7 +384,7 @@ class ContractSolc(CallerContextExpression):
         func.set_contract(self._contract)
         func.set_contract_declarer(self._contract)
 
-        func_parser = FunctionSolc(func, function_data, self, self._slither_parser)
+        func_parser = FunctionSolc(func, function_data, self, self._slither_parser)  # type: ignore
         self._contract.compilation_unit.add_function(func)
         self._functions_no_params.append(func_parser)
         self._functions_parser.append(func_parser)
@@ -395,7 +396,7 @@ class ContractSolc(CallerContextExpression):
         for function in self._functionsNotParsed:
             self._parse_function(function)
 
-        self._functionsNotParsed = None
+        self._functionsNotParsed = []
 
     # endregion
     ###################################################################################
@@ -439,7 +440,8 @@ class ContractSolc(CallerContextExpression):
                 Cls_parser,
                 self._modifiers_parser,
             )
-            self._contract.set_modifiers(modifiers)
+            # modifiers will be using Modifier so we can ignore the next type check
+            self._contract.set_modifiers(modifiers)  # type: ignore
         except (VariableNotFound, KeyError) as e:
             self.log_incorrect_parsing(f"Missing params {e}")
         self._modifiers_no_params = []
@@ -459,7 +461,8 @@ class ContractSolc(CallerContextExpression):
                 Cls_parser,
                 self._functions_parser,
             )
-            self._contract.set_functions(functions)
+            # function will be using FunctionContract so we can ignore the next type check
+            self._contract.set_functions(functions)  # type: ignore
         except (VariableNotFound, KeyError) as e:
             self.log_incorrect_parsing(f"Missing params {e}")
         self._functions_no_params = []
@@ -470,7 +473,7 @@ class ContractSolc(CallerContextExpression):
         Cls_parser: Callable,
         element_parser: FunctionSolc,
         explored_reference_id: Set[str],
-        parser: List[FunctionSolc],
+        parser: Union[List[FunctionSolc], List[ModifierSolc]],
         all_elements: Dict[str, Function],
     ) -> None:
         elem = Cls(self._contract.compilation_unit)
@@ -508,13 +511,13 @@ class ContractSolc(CallerContextExpression):
 
     def _analyze_params_elements(  # pylint: disable=too-many-arguments,too-many-locals
         self,
-        elements_no_params: List[FunctionSolc],
+        elements_no_params: Sequence[FunctionSolc],
         getter: Callable[["ContractSolc"], List[FunctionSolc]],
         getter_available: Callable[[Contract], List[FunctionContract]],
         Cls: Callable,
         Cls_parser: Callable,
-        parser: List[FunctionSolc],
-    ) -> Dict[str, Union[FunctionContract, Modifier]]:
+        parser: Union[List[FunctionSolc], List[ModifierSolc]],
+    ) -> Dict[str, Function]:
         """
         Analyze the parameters of the given elements (Function or Modifier).
         The function iterates over the inheritance to create an instance or inherited elements (Function or Modifier)
@@ -526,13 +529,13 @@ class ContractSolc(CallerContextExpression):
         :param Cls: Class to create for collision
         :return:
         """
-        all_elements = {}
+        all_elements: Dict[str, Function] = {}
 
-        explored_reference_id = set()
+        explored_reference_id: Set[str] = set()
         try:
             for father in self._contract.inheritance:
                 father_parser = self._slither_parser.underlying_contract_to_parser[father]
-                for element_parser in getter(father_parser):
+                for element_parser in getter(father_parser):  # type: ignore
                     self._analyze_params_element(
                         Cls, Cls_parser, element_parser, explored_reference_id, parser, all_elements
                     )
@@ -597,7 +600,7 @@ class ContractSolc(CallerContextExpression):
             if self.is_compact_ast:
                 for using_for in self._usingForNotParsed:
                     if "typeName" in using_for and using_for["typeName"]:
-                        type_name = parse_type(using_for["typeName"], self)
+                        type_name: USING_FOR_KEY = parse_type(using_for["typeName"], self)
                     else:
                         type_name = "*"
                     if type_name not in self._contract.using_for:
@@ -616,7 +619,7 @@ class ContractSolc(CallerContextExpression):
                     assert children and len(children) <= 2
                     if len(children) == 2:
                         new = parse_type(children[0], self)
-                        old = parse_type(children[1], self)
+                        old: USING_FOR_KEY = parse_type(children[1], self)
                     else:
                         new = parse_type(children[0], self)
                         old = "*"
@@ -627,7 +630,7 @@ class ContractSolc(CallerContextExpression):
         except (VariableNotFound, KeyError) as e:
             self.log_incorrect_parsing(f"Missing using for {e}")
 
-    def _analyze_function_list(self, function_list: List, type_name: Type) -> None:
+    def _analyze_function_list(self, function_list: List, type_name: USING_FOR_KEY) -> None:
         for f in function_list:
             full_name_split = f["function"]["name"].split(".")
             if len(full_name_split) == 1:
@@ -646,7 +649,9 @@ class ContractSolc(CallerContextExpression):
                 function_name = full_name_split[2]
                 self._analyze_library_function(library_name, function_name, type_name)
 
-    def _check_aliased_import(self, first_part: str, function_name: str, type_name: Type) -> None:
+    def _check_aliased_import(
+        self, first_part: str, function_name: str, type_name: USING_FOR_KEY
+    ) -> None:
         # We check if the first part appear as alias for an import
         # if it is then function_name must be a top level function
         # otherwise it's a library function
@@ -656,13 +661,13 @@ class ContractSolc(CallerContextExpression):
                 return
         self._analyze_library_function(first_part, function_name, type_name)
 
-    def _analyze_top_level_function(self, function_name: str, type_name: Type) -> None:
+    def _analyze_top_level_function(self, function_name: str, type_name: USING_FOR_KEY) -> None:
         for tl_function in self.compilation_unit.functions_top_level:
             if tl_function.name == function_name:
                 self._contract.using_for[type_name].append(tl_function)
 
     def _analyze_library_function(
-        self, library_name: str, function_name: str, type_name: Type
+        self, library_name: str, function_name: str, type_name: USING_FOR_KEY
     ) -> None:
         # Get the library function
         found = False
@@ -689,22 +694,13 @@ class ContractSolc(CallerContextExpression):
                 # for enum, we can parse and analyze it
                 # at the same time
                 self._analyze_enum(enum)
-            self._enumsNotParsed = None
+            self._enumsNotParsed = []
         except (VariableNotFound, KeyError) as e:
             self.log_incorrect_parsing(f"Missing enum {e}")
 
     def _analyze_enum(
         self,
-        enum: Dict[
-            str,
-            Union[
-                str,
-                int,
-                List[Dict[str, Union[int, str]]],
-                Dict[str, str],
-                List[Dict[str, Union[Dict[str, str], int, str]]],
-            ],
-        ],
+        enum: Dict,
     ) -> None:
         # Enum can be parsed in one pass
         if self.is_compact_ast:
@@ -753,13 +749,13 @@ class ContractSolc(CallerContextExpression):
                 event.set_contract(self._contract)
                 event.set_offset(event_to_parse["src"], self._contract.compilation_unit)
 
-                event_parser = EventSolc(event, event_to_parse, self)
-                event_parser.analyze(self)
+                event_parser = EventSolc(event, event_to_parse, self)  # type: ignore
+                event_parser.analyze(self)  # type: ignore
                 self._contract.events_as_dict[event.full_name] = event
         except (VariableNotFound, KeyError) as e:
             self.log_incorrect_parsing(f"Missing event {e}")
 
-        self._eventsNotParsed = None
+        self._eventsNotParsed = []
 
     # endregion
     ###################################################################################
@@ -768,7 +764,7 @@ class ContractSolc(CallerContextExpression):
     ###################################################################################
     ###################################################################################
 
-    def delete_content(self):
+    def delete_content(self) -> None:
         """
         Remove everything not parsed from the contract
         This is used only if something went wrong with the inheritance parsing
@@ -810,7 +806,7 @@ class ContractSolc(CallerContextExpression):
     ###################################################################################
     ###################################################################################
 
-    def __hash__(self):
+    def __hash__(self) -> int:
         return self._contract.id
 
     # endregion
diff --git a/slither/solc_parsing/declarations/function.py b/slither/solc_parsing/declarations/function.py
index 9671d9bbe..ba2f225f0 100644
--- a/slither/solc_parsing/declarations/function.py
+++ b/slither/solc_parsing/declarations/function.py
@@ -242,7 +242,7 @@ class FunctionSolc(CallerContextExpression):
         if "payable" in attributes:
             self._function.payable = attributes["payable"]
 
-    def analyze_params(self):
+    def analyze_params(self) -> None:
         # Can be re-analyzed due to inheritance
         if self._params_was_analyzed:
             return
@@ -272,7 +272,7 @@ class FunctionSolc(CallerContextExpression):
         if returns:
             self._parse_returns(returns)
 
-    def analyze_content(self):
+    def analyze_content(self) -> None:
         if self._content_was_analyzed:
             return
 
@@ -308,8 +308,8 @@ class FunctionSolc(CallerContextExpression):
         for node_parser in self._node_to_nodesolc.values():
             node_parser.analyze_expressions(self)
 
-        for node_parser in self._node_to_yulobject.values():
-            node_parser.analyze_expressions()
+        for yul_parser in self._node_to_yulobject.values():
+            yul_parser.analyze_expressions()
 
         self._rewrite_ternary_as_if_else()
 
@@ -1297,7 +1297,7 @@ class FunctionSolc(CallerContextExpression):
                     son.remove_father(node)
                 node.set_sons(new_sons)
 
-    def _remove_alone_endif(self):
+    def _remove_alone_endif(self) -> None:
         """
         Can occur on:
         if(..){
diff --git a/slither/solc_parsing/variables/variable_declaration.py b/slither/solc_parsing/variables/variable_declaration.py
index d21d89875..69b72a521 100644
--- a/slither/solc_parsing/variables/variable_declaration.py
+++ b/slither/solc_parsing/variables/variable_declaration.py
@@ -1,6 +1,6 @@
 import logging
 import re
-from typing import Dict, Optional
+from typing import Dict, Optional, Union
 
 from slither.solc_parsing.declarations.caller_context import CallerContextExpression
 from slither.solc_parsing.expressions.expression_parsing import parse_expression
@@ -42,12 +42,12 @@ class VariableDeclarationSolc:
 
         self._variable = variable
         self._was_analyzed = False
-        self._elem_to_parse = None
-        self._initializedNotParsed = None
+        self._elem_to_parse: Optional[Union[Dict, UnknownType]] = None
+        self._initializedNotParsed: Optional[Dict] = None
 
         self._is_compact_ast = False
 
-        self._reference_id = None
+        self._reference_id: Optional[int] = None
 
         if "nodeType" in variable_data:
             self._is_compact_ast = True
@@ -87,7 +87,7 @@ class VariableDeclarationSolc:
                 declaration = variable_data["children"][0]
                 self._init_from_declaration(declaration, init)
             elif nodeType == "VariableDeclaration":
-                self._init_from_declaration(variable_data, False)
+                self._init_from_declaration(variable_data, None)
             else:
                 raise ParsingError(f"Incorrect variable declaration type {nodeType}")
 
@@ -101,6 +101,7 @@ class VariableDeclarationSolc:
         Return the solc id. It can be compared with the referencedDeclaration attr
         Returns None if it was not parsed (legacy AST)
         """
+        assert self._reference_id
         return self._reference_id
 
     def _handle_comment(self, attributes: Dict) -> None:
@@ -127,7 +128,7 @@ class VariableDeclarationSolc:
             self._variable.visibility = "internal"
 
     def _init_from_declaration(
-        self, var: Dict, init: Optional[bool]
+        self, var: Dict, init: Optional[Dict]
     ) -> None:  # pylint: disable=too-many-branches
         if self._is_compact_ast:
             attributes = var
@@ -195,7 +196,7 @@ class VariableDeclarationSolc:
                 self._initializedNotParsed = init
             elif len(var["children"]) in [0, 1]:
                 self._variable.initialized = False
-                self._initializedNotParsed = []
+                self._initializedNotParsed = None
             else:
                 assert len(var["children"]) == 2
                 self._variable.initialized = True
@@ -212,5 +213,6 @@ class VariableDeclarationSolc:
             self._elem_to_parse = None
 
         if self._variable.initialized:
+            assert self._initializedNotParsed
             self._variable.expression = parse_expression(self._initializedNotParsed, caller_context)
             self._initializedNotParsed = None
diff --git a/slither/tools/doctor/checks/versions.py b/slither/tools/doctor/checks/versions.py
index ec7ef1d1f..00662b3e9 100644
--- a/slither/tools/doctor/checks/versions.py
+++ b/slither/tools/doctor/checks/versions.py
@@ -1,6 +1,6 @@
 from importlib import metadata
 import json
-from typing import Optional
+from typing import Optional, Any
 import urllib
 
 from packaging.version import parse, Version
@@ -17,6 +17,7 @@ def get_installed_version(name: str) -> Optional[Version]:
 
 def get_github_version(name: str) -> Optional[Version]:
     try:
+        # type: ignore
         with urllib.request.urlopen(
             f"https://api.github.com/repos/crytic/{name}/releases/latest"
         ) as response:
@@ -27,7 +28,7 @@ def get_github_version(name: str) -> Optional[Version]:
         return None
 
 
-def show_versions(**_kwargs) -> None:
+def show_versions(**_kwargs: Any) -> None:
     versions = {
         "Slither": (get_installed_version("slither-analyzer"), get_github_version("slither")),
         "crytic-compile": (
diff --git a/slither/tools/read_storage/utils/utils.py b/slither/tools/read_storage/utils/utils.py
index 3e51e2181..4a04a5b6d 100644
--- a/slither/tools/read_storage/utils/utils.py
+++ b/slither/tools/read_storage/utils/utils.py
@@ -2,6 +2,7 @@ from typing import Union
 
 from eth_typing.evm import ChecksumAddress
 from eth_utils import to_int, to_text, to_checksum_address
+from web3 import Web3
 
 
 def get_offset_value(hex_bytes: bytes, offset: int, size: int) -> bytes:
@@ -48,7 +49,7 @@ def coerce_type(
     if "address" in solidity_type:
         if not isinstance(value, (str, bytes)):
             raise TypeError
-        return to_checksum_address(value)
+        return to_checksum_address(value)  # type: ignore
 
     if not isinstance(value, bytes):
         raise TypeError
@@ -56,7 +57,7 @@ def coerce_type(
 
 
 def get_storage_data(
-    web3, checksum_address: ChecksumAddress, slot: bytes, block: Union[int, str]
+    web3: Web3, checksum_address: ChecksumAddress, slot: bytes, block: Union[int, str]
 ) -> bytes:
     """
     Retrieves the storage data from the blockchain at target address and slot.
diff --git a/slither/tools/upgradeability/checks/variable_initialization.py b/slither/tools/upgradeability/checks/variable_initialization.py
index e8ae9b26c..b4535ddfe 100644
--- a/slither/tools/upgradeability/checks/variable_initialization.py
+++ b/slither/tools/upgradeability/checks/variable_initialization.py
@@ -1,7 +1,11 @@
+from typing import List
+
 from slither.tools.upgradeability.checks.abstract_checks import (
     CheckClassification,
     AbstractCheck,
+    CHECK_INFO,
 )
+from slither.utils.output import Output
 
 
 class VariableWithInit(AbstractCheck):
@@ -37,11 +41,11 @@ Using initialize functions to write initial values in state variables.
 
     REQUIRE_CONTRACT = True
 
-    def _check(self):
+    def _check(self) -> List[Output]:
         results = []
         for s in self.contract.state_variables_ordered:
             if s.initialized and not (s.is_constant or s.is_immutable):
-                info = [s, " is a state variable with an initial value.\n"]
+                info: CHECK_INFO = [s, " is a state variable with an initial value.\n"]
                 json = self.generate_result(info)
                 results.append(json)
         return results
diff --git a/slither/tools/upgradeability/checks/variables_order.py b/slither/tools/upgradeability/checks/variables_order.py
index 030fb0f65..fc83c44c6 100644
--- a/slither/tools/upgradeability/checks/variables_order.py
+++ b/slither/tools/upgradeability/checks/variables_order.py
@@ -1,7 +1,12 @@
+from typing import List
+
+from slither.core.declarations import Contract
 from slither.tools.upgradeability.checks.abstract_checks import (
     CheckClassification,
     AbstractCheck,
+    CHECK_INFO,
 )
+from slither.utils.output import Output
 
 
 class MissingVariable(AbstractCheck):
@@ -45,9 +50,12 @@ Do not change the order of the state variables in the updated contract.
     REQUIRE_CONTRACT = True
     REQUIRE_CONTRACT_V2 = True
 
-    def _check(self):
+    def _check(self) -> List[Output]:
         contract1 = self.contract
         contract2 = self.contract_v2
+
+        assert contract2
+
         order1 = [
             variable
             for variable in contract1.state_variables_ordered
@@ -63,7 +71,7 @@ Do not change the order of the state variables in the updated contract.
         for idx, _ in enumerate(order1):
             variable1 = order1[idx]
             if len(order2) <= idx:
-                info = ["Variable missing in ", contract2, ": ", variable1, "\n"]
+                info: CHECK_INFO = ["Variable missing in ", contract2, ": ", variable1, "\n"]
                 json = self.generate_result(info)
                 results.append(json)
 
@@ -108,13 +116,14 @@ Avoid variables in the proxy. If a variable is in the proxy, ensure it has the s
     REQUIRE_CONTRACT = True
     REQUIRE_PROXY = True
 
-    def _contract1(self):
+    def _contract1(self) -> Contract:
         return self.contract
 
-    def _contract2(self):
+    def _contract2(self) -> Contract:
+        assert self.proxy
         return self.proxy
 
-    def _check(self):
+    def _check(self) -> List[Output]:
         contract1 = self._contract1()
         contract2 = self._contract2()
         order1 = [
@@ -128,7 +137,7 @@ Avoid variables in the proxy. If a variable is in the proxy, ensure it has the s
             if not (variable.is_constant or variable.is_immutable)
         ]
 
-        results = []
+        results: List[Output] = []
         for idx, _ in enumerate(order1):
             if len(order2) <= idx:
                 # Handle by MissingVariable
@@ -137,7 +146,7 @@ Avoid variables in the proxy. If a variable is in the proxy, ensure it has the s
             variable1 = order1[idx]
             variable2 = order2[idx]
             if (variable1.name != variable2.name) or (variable1.type != variable2.type):
-                info = [
+                info: CHECK_INFO = [
                     "Different variables between ",
                     contract1,
                     " and ",
@@ -190,7 +199,8 @@ Respect the variable order of the original contract in the updated contract.
     REQUIRE_PROXY = False
     REQUIRE_CONTRACT_V2 = True
 
-    def _contract2(self):
+    def _contract2(self) -> Contract:
+        assert self.contract_v2
         return self.contract_v2
 
 
@@ -235,13 +245,14 @@ Avoid variables in the proxy. If a variable is in the proxy, ensure it has the s
     REQUIRE_CONTRACT = True
     REQUIRE_PROXY = True
 
-    def _contract1(self):
+    def _contract1(self) -> Contract:
         return self.contract
 
-    def _contract2(self):
+    def _contract2(self) -> Contract:
+        assert self.proxy
         return self.proxy
 
-    def _check(self):
+    def _check(self) -> List[Output]:
         contract1 = self._contract1()
         contract2 = self._contract2()
         order1 = [
@@ -264,7 +275,7 @@ Avoid variables in the proxy. If a variable is in the proxy, ensure it has the s
 
         while idx < len(order2):
             variable2 = order2[idx]
-            info = ["Extra variables in ", contract2, ": ", variable2, "\n"]
+            info: CHECK_INFO = ["Extra variables in ", contract2, ": ", variable2, "\n"]
             json = self.generate_result(info)
             results.append(json)
             idx = idx + 1
@@ -299,5 +310,6 @@ Ensure that all the new variables are expected.
     REQUIRE_PROXY = False
     REQUIRE_CONTRACT_V2 = True
 
-    def _contract2(self):
+    def _contract2(self) -> Contract:
+        assert self.contract_v2
         return self.contract_v2
diff --git a/slither/visitors/expression/constants_folding.py b/slither/visitors/expression/constants_folding.py
index 7b1a8f8ee..12eb6be9d 100644
--- a/slither/visitors/expression/constants_folding.py
+++ b/slither/visitors/expression/constants_folding.py
@@ -104,7 +104,7 @@ class ConstantFolding(ExpressionVisitor):
             and isinstance(left, (int, Fraction))
             and isinstance(right, (int, Fraction))
         ):
-            set_val(expression, left**right) #type: ignore
+            set_val(expression, left**right)  # type: ignore
         elif (
             expression.type == BinaryOperationType.MULTIPLICATION
             and isinstance(left, (int, Fraction))
diff --git a/tests/test_ssa_generation.py b/tests/test_ssa_generation.py
index 9bb008fdf..c7bc8d5cc 100644
--- a/tests/test_ssa_generation.py
+++ b/tests/test_ssa_generation.py
@@ -6,7 +6,7 @@ from collections import defaultdict
 from contextlib import contextmanager
 from inspect import getsourcefile
 from tempfile import NamedTemporaryFile
-from typing import Union, List, Optional
+from typing import Union, List, Optional, Dict, Callable
 
 import pytest
 from solc_select import solc_select
@@ -15,6 +15,7 @@ from solc_select.solc_select import valid_version as solc_valid_version
 from slither import Slither
 from slither.core.cfg.node import Node, NodeType
 from slither.core.declarations import Function, Contract
+from slither.core.variables.local_variable import LocalVariable
 from slither.core.variables.state_variable import StateVariable
 from slither.slithir.operations import (
     OperationWithLValue,
@@ -34,10 +35,11 @@ from slither.slithir.variables import (
     ReferenceVariable,
     LocalIRVariable,
     StateIRVariable,
+    TemporaryVariableSSA,
 )
 
 # Directory of currently executing script. Will be used as basis for temporary file names.
-SCRIPT_DIR = pathlib.Path(getsourcefile(lambda: 0)).parent
+SCRIPT_DIR = pathlib.Path(getsourcefile(lambda: 0)).parent  # type:ignore
 
 
 def valid_version(ver: str) -> bool:
@@ -53,15 +55,15 @@ def valid_version(ver: str) -> bool:
         return False
 
 
-def have_ssa_if_ir(function: Function):
+def have_ssa_if_ir(function: Function) -> None:
     """Verifies that all nodes in a function that have IR also have SSA IR"""
     for n in function.nodes:
         if n.irs:
             assert n.irs_ssa
 
 
-# pylint: disable=too-many-branches
-def ssa_basic_properties(function: Function):
+# pylint: disable=too-many-branches, too-many-locals
+def ssa_basic_properties(function: Function) -> None:
     """Verifies that basic properties of ssa holds
 
     1. Every name is defined only once
@@ -75,12 +77,14 @@ def ssa_basic_properties(function: Function):
     """
     ssa_lvalues = set()
     ssa_rvalues = set()
-    lvalue_assignments = {}
+    lvalue_assignments: Dict[str, int] = {}
 
     for n in function.nodes:
         for ir in n.irs:
-            if isinstance(ir, OperationWithLValue):
+            if isinstance(ir, OperationWithLValue) and ir.lvalue:
                 name = ir.lvalue.name
+                if name is None:
+                    continue
                 if name in lvalue_assignments:
                     lvalue_assignments[name] += 1
                 else:
@@ -93,8 +97,9 @@ def ssa_basic_properties(function: Function):
                 ssa_lvalues.add(ssa.lvalue)
 
                 # 2 (if Local/State Var)
-                if isinstance(ssa.lvalue, (StateIRVariable, LocalIRVariable)):
-                    assert ssa.lvalue.index > 0
+                ssa_lvalue = ssa.lvalue
+                if isinstance(ssa_lvalue, (StateIRVariable, LocalIRVariable)):
+                    assert ssa_lvalue.index > 0
 
             for rvalue in filter(
                 lambda x: not isinstance(x, (StateIRVariable, Constant)), ssa.read
@@ -111,15 +116,18 @@ def ssa_basic_properties(function: Function):
             undef_vars.add(rvalue.non_ssa_version)
 
     # 4
-    ssa_defs = defaultdict(int)
+    ssa_defs: Dict[str, int] = defaultdict(int)
     for v in ssa_lvalues:
-        ssa_defs[v.name] += 1
+        if v and v.name:
+            ssa_defs[v.name] += 1
 
-    for (k, n) in lvalue_assignments.items():
-        assert ssa_defs[k] >= n
+    for (k, count) in lvalue_assignments.items():
+        assert ssa_defs[k] >= count
 
     # Helper 5/6
-    def check_property_5_and_6(variables, ssavars):
+    def check_property_5_and_6(
+        variables: List[LocalVariable], ssavars: List[LocalIRVariable]
+    ) -> None:
         for var in filter(lambda x: x.name, variables):
             ssa_vars = [x for x in ssavars if x.non_ssa_version == var]
             assert len(ssa_vars) == 1
@@ -136,7 +144,7 @@ def ssa_basic_properties(function: Function):
     check_property_5_and_6(function.returns, function.returns_ssa)
 
 
-def ssa_phi_node_properties(f: Function):
+def ssa_phi_node_properties(f: Function) -> None:
     """Every phi-function should have as many args as predecessors
 
     This does not apply if the phi-node refers to state variables,
@@ -152,7 +160,7 @@ def ssa_phi_node_properties(f: Function):
 
 
 # TODO (hbrodin): This should probably go into another file, not specific to SSA
-def dominance_properties(f: Function):
+def dominance_properties(f: Function) -> None:
     """Verifies properties related to dominators holds
 
     1. Every node have an immediate dominator except entry_node which have none
@@ -180,14 +188,16 @@ def dominance_properties(f: Function):
             assert find_path(node.immediate_dominator, node)
 
 
-def phi_values_inserted(f: Function):
+def phi_values_inserted(f: Function) -> None:
     """Verifies that phi-values are inserted at the right places
 
     For every node that has a dominance frontier, any def (including
     phi) should be a phi function in its dominance frontier
     """
 
-    def have_phi_for_var(node: Node, var):
+    def have_phi_for_var(
+        node: Node, var: Union[StateIRVariable, LocalIRVariable, TemporaryVariableSSA]
+    ) -> bool:
         """Checks if a node has a phi-instruction for var
 
         The ssa version would ideally be checked, but then
@@ -198,7 +208,14 @@ def phi_values_inserted(f: Function):
         non_ssa = var.non_ssa_version
         for ssa in node.irs_ssa:
             if isinstance(ssa, Phi):
-                if non_ssa in map(lambda ssa_var: ssa_var.non_ssa_version, ssa.read):
+                if non_ssa in map(
+                    lambda ssa_var: ssa_var.non_ssa_version,
+                    [
+                        r
+                        for r in ssa.read
+                        if isinstance(r, (StateIRVariable, LocalIRVariable, TemporaryVariableSSA))
+                    ],
+                ):
                     return True
         return False
 
@@ -206,12 +223,15 @@ def phi_values_inserted(f: Function):
         for df in node.dominance_frontier:
             for ssa in node.irs_ssa:
                 if isinstance(ssa, OperationWithLValue):
-                    if is_used_later(node, ssa.lvalue):
-                        assert have_phi_for_var(df, ssa.lvalue)
+                    ssa_lvalue = ssa.lvalue
+                    if isinstance(
+                        ssa_lvalue, (StateIRVariable, LocalIRVariable, TemporaryVariableSSA)
+                    ) and is_used_later(node, ssa_lvalue):
+                        assert have_phi_for_var(df, ssa_lvalue)
 
 
 @contextmanager
-def select_solc_version(version: Optional[str]):
+def select_solc_version(version: Optional[str]) -> None:
     """Selects solc version to use for running tests.
 
     If no version is provided, latest is used."""
@@ -256,17 +276,17 @@ def slither_from_source(source_code: str, solc_version: Optional[str] = None):
         pathlib.Path(fname).unlink()
 
 
-def verify_properties_hold(source_code_or_slither: Union[str, Slither]):
+def verify_properties_hold(source_code_or_slither: Union[str, Slither]) -> None:
     """Ensures that basic properties of SSA hold true"""
 
-    def verify_func(func: Function):
+    def verify_func(func: Function) -> None:
         have_ssa_if_ir(func)
         phi_values_inserted(func)
         ssa_basic_properties(func)
         ssa_phi_node_properties(func)
         dominance_properties(func)
 
-    def verify(slither):
+    def verify(slither: Slither) -> None:
         for cu in slither.compilation_units:
             for func in cu.functions_and_modifiers:
                 _dump_function(func)
@@ -280,11 +300,12 @@ def verify_properties_hold(source_code_or_slither: Union[str, Slither]):
     if isinstance(source_code_or_slither, Slither):
         verify(source_code_or_slither)
     else:
+        slither: Slither
         with slither_from_source(source_code_or_slither) as slither:
             verify(slither)
 
 
-def _dump_function(f: Function):
+def _dump_function(f: Function) -> None:
     """Helper function to print nodes/ssa ir for a function or modifier"""
     print(f"---- {f.name} ----")
     for n in f.nodes:
@@ -294,13 +315,13 @@ def _dump_function(f: Function):
     print("")
 
 
-def _dump_functions(c: Contract):
+def _dump_functions(c: Contract) -> None:
     """Helper function to print functions and modifiers of a contract"""
     for f in c.functions_and_modifiers:
         _dump_function(f)
 
 
-def get_filtered_ssa(f: Union[Function, Node], flt) -> List[Operation]:
+def get_filtered_ssa(f: Union[Function, Node], flt: Callable) -> List[Operation]:
     """Returns a list of all ssanodes filtered by filter for all nodes in function f"""
     if isinstance(f, Function):
         return [ssanode for node in f.nodes for ssanode in node.irs_ssa if flt(ssanode)]
@@ -314,7 +335,7 @@ def get_ssa_of_type(f: Union[Function, Node], ssatype) -> List[Operation]:
     return get_filtered_ssa(f, lambda ssanode: isinstance(ssanode, ssatype))
 
 
-def test_multi_write():
+def test_multi_write() -> None:
     contract = """
     pragma solidity ^0.8.11;
     contract Test {
@@ -327,7 +348,7 @@ def test_multi_write():
     verify_properties_hold(contract)
 
 
-def test_single_branch_phi():
+def test_single_branch_phi() -> None:
     contract = """
         pragma solidity ^0.8.11;
         contract Test {
@@ -342,7 +363,7 @@ def test_single_branch_phi():
     verify_properties_hold(contract)
 
 
-def test_basic_phi():
+def test_basic_phi() -> None:
     contract = """
     pragma solidity ^0.8.11;
     contract Test {
@@ -359,7 +380,7 @@ def test_basic_phi():
     verify_properties_hold(contract)
 
 
-def test_basic_loop_phi():
+def test_basic_loop_phi() -> None:
     contract = """
     pragma solidity ^0.8.11;
     contract Test {
@@ -375,7 +396,7 @@ def test_basic_loop_phi():
 
 
 @pytest.mark.skip(reason="Fails in current slither version. Fix in #1102.")
-def test_phi_propagation_loop():
+def test_phi_propagation_loop() -> None:
     contract = """
      pragma solidity ^0.8.11;
      contract Test {
@@ -396,7 +417,7 @@ def test_phi_propagation_loop():
 
 
 @pytest.mark.skip(reason="Fails in current slither version. Fix in #1102.")
-def test_free_function_properties():
+def test_free_function_properties() -> None:
     contract = """
         pragma solidity ^0.8.11;
 
@@ -417,7 +438,7 @@ def test_free_function_properties():
     verify_properties_hold(contract)
 
 
-def test_ssa_inter_transactional():
+def test_ssa_inter_transactional() -> None:
     source = """
     pragma solidity ^0.8.11;
     contract A {
@@ -460,7 +481,7 @@ def test_ssa_inter_transactional():
 
 
 @pytest.mark.skip(reason="Fails in current slither version. Fix in #1102.")
-def test_ssa_phi_callbacks():
+def test_ssa_phi_callbacks() -> None:
     source = """
     pragma solidity ^0.8.11;
     contract A {
@@ -519,7 +540,7 @@ def test_ssa_phi_callbacks():
 
 
 @pytest.mark.skip(reason="Fails in current slither version. Fix in #1102.")
-def test_storage_refers_to():
+def test_storage_refers_to() -> None:
     """Test the storage aspects of the SSA IR
 
     When declaring a var as being storage, start tracking what storage it refers_to.