Merge branch 'master' into printer-human-readable

.gitignore

@@ -101,3 +101,6 @@ ENV/
 .mypy_cache
 
 *.sw*
+
+# PyCharm project dir
+.idea/

README.md

@@ -1,7 +1,7 @@
 # Slither, the Solidity source analyzer
 [![Build Status](https://travis-ci.com/trailofbits/slither.svg?token=JEF97dFy1QsDCfQ2Wusd&branch=master)](https://travis-ci.com/trailofbits/slither)
 
-Slither is a Solidity static analysis framework. It provides an API to easily manipulate Solidity code. In addition to exposing a Solidity contracts AST, Slither provides many APIs to quickly check local and state variable usage.
+Slither is a Solidity static analysis framework written in Python 3. It provides an API to easily manipulate Solidity code. In addition to exposing a Solidity contracts AST, Slither provides many APIs to quickly check local and state variable usage.
 
 With Slither you can:
 - Detect vulnerabilities
@@ -11,15 +11,14 @@ With Slither you can:
 
 ## How to install
 
-Slither uses Python 2.
+Slither uses Python 3.6.
 
-Use pip to install the dependencies:
 
 ```bash
-$ pip install -U -r requirements.txt
+$ python setup.py install
 ```
 
-You may also want solc, which can be installed using homebrew:
+You may also want solc, the Solidity compiler, which can be installed using homebrew:
 
 ```bash
 $ brew update
@@ -40,11 +39,11 @@ $ sudo apt-get install solc
 ## How to use
 
 ``` 
-$ slither.py file.sol
+$ slither file.sol
 ``` 
 
 ``` 
-$ slither.py examples/uninitialized.sol
+$ slither examples/uninitialized.sol
 [..]
 INFO:Detectors:Uninitialized state variables in examples/uninitialized.sol, Contract: Uninitialized, Vars: destination, Used in ['transfer']
 [..]

examples/scripts/functions_called.py

@@ -14,4 +14,4 @@ all_calls = entry_point.all_calls()
 all_calls_formated = [f.contract.name + '.' + f.name for f in all_calls]
 
 # Print the result
-print 'From entry_point the functions reached are {}'.format(all_calls_formated)
+print('From entry_point the functions reached are {}'.format(all_calls_formated))

examples/scripts/functions_writing.py

@@ -13,4 +13,4 @@ var_a = contract.get_state_variable_from_name('a')
 functions_writing_a = contract.get_functions_writing_variable(var_a)
 
 # Print the result
-print 'The function writing "a" are {}'.format([f.name for f in functions_writing_a])
+print('The function writing "a" are {}'.format([f.name for f in functions_writing_a]))

examples/scripts/variable_in_condition.py

@@ -17,4 +17,4 @@ function_using_a_as_condition = [f for f in functions_reading_a if\
                                  f.is_reading_in_require_or_assert(var_a)]
 
 # Print the result
-print 'The function using "a" in condition are {}'.format([f.name for f in function_using_a_as_condition])
+print('The function using "a" in condition are {}'.format([f.name for f in function_using_a_as_condition]))

requirements.txt

@@ -1 +0,0 @@
-prettytable

setup.py

@@ -0,0 +1,19 @@
+from setuptools import setup, find_packages
+
+setup(
+    name='Slither',
+    description='Slither is a Solidity static analysis framework written in Python 3.',
+    url='https://github.com/trailofbits/slither',
+    author='Trail of Bits',
+    version='0.1',
+    packages=find_packages(),
+    python_requires='>=3.6',
+    install_requires=['prettytable>=0.7.2'],
+    license='AGPL-3.0',
+    long_description=open('README.md').read(),
+    entry_points={
+        'console_scripts': [
+            'slither = slither.__main__:main'
+        ]
+    }
+)

slither/__init__.py

@@ -0,0 +1 @@
+from .slither import Slither

slither/__main__.py

@@ -1,22 +1,21 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python3
 
 import sys
 import argparse
 import logging
-import subprocess
 import traceback
 import os
 import glob
 import json
 
 from slither.slither import Slither
-from slither.utils.colors import red
 from slither.detectors.detectors import Detectors
 from slither.printers.printers import Printers
 
 logging.basicConfig()
 logger = logging.getLogger("Slither")
 
+
 def determineChecks(detectors, args):
     if args.low:
         return detectors.low
@@ -42,17 +41,19 @@ def process(filename, args, detectors, printers):
         results = [item for sublist in results for item in sublist] #flatten
         return results
 
+
 def output_json(results, filename):
     with open(filename, 'w') as f:
         json.dump(results, f)
 
+
 def exit(results):
     if not results:
         sys.exit(0)
     sys.exit(len(results))
 
-if __name__ == '__main__':
 
+def main():
     detectors = Detectors()
     printers = Printers()
 
@@ -102,8 +103,7 @@ if __name__ == '__main__':
                         action='store',
                         default=None)
 
-
-    for detector_name, Detector in detectors.detectors.iteritems():
+    for detector_name, Detector in detectors.detectors.items():
         detector_arg = '--{}'.format(Detector.ARGUMENT)
         detector_help = 'Detection of ' + Detector.HELP
         parser.add_argument(detector_arg,
@@ -112,7 +112,7 @@ if __name__ == '__main__':
                             dest="detectors_to_run",
                             const=detector_name)
 
-    for printer_name, Printer in printers.printers.iteritems():
+    for printer_name, Printer in printers.printers.items():
         printer_arg = '--{}'.format(Printer.ARGUMENT)
         printer_help = Printer.HELP
         parser.add_argument(printer_arg,
@@ -166,8 +166,11 @@ if __name__ == '__main__':
         logger.info('%s analyzed, %d result(s) found', filename, len(results))
         exit(results)
 
-
     except Exception as e:
         logging.error('Error in %s'%sys.argv[1])
         logging.error(traceback.format_exc())
         sys.exit(-1)
+
+
+if __name__ == '__main__':
+    main()

slither/core/cfg/nodeType.py

@@ -1,4 +1,4 @@
-class NodeType(object):
+class NodeType:
 
     ENTRYPOINT = 0x0  # no expression
 

slither/core/children/childContract.py

@@ -1,5 +1,5 @@
 
-class ChildContract(object):
+class ChildContract:
 
     def __init__(self):
         super(ChildContract, self).__init__()

slither/core/children/childEvent.py

@@ -1,5 +1,5 @@
 
-class ChildEvent(object):
+class ChildEvent:
     def __init__(self):
         super(ChildEvent, self).__init__()
         self._event = None

slither/core/children/childFunction.py

@@ -1,5 +1,5 @@
 
-class ChildFunction(object):
+class ChildFunction:
     def __init__(self):
         super(ChildFunction, self).__init__()
         self._function = None

slither/core/children/childSlither.py

@@ -1,5 +1,5 @@
 
-class ChildSlither(object):
+class ChildSlither:
 
     def __init__(self):
         super(ChildSlither, self).__init__()

slither/core/children/childStructure.py

@@ -1,5 +1,5 @@
 
-class ChildStructure(object):
+class ChildStructure:
 
     def __init__(self):
         super(ChildStructure, self).__init__()

slither/core/context/context.py

@@ -1,4 +1,4 @@
-class Context(object):
+class Context:
 
     def __init__(self):
         super(Context, self).__init__()

slither/core/declarations/contract.py

@@ -32,12 +32,12 @@ class Contract(ChildSlither, SourceMapping):
 
 
     def __eq__(self, other):
-        if isinstance(other, unicode):
+        if isinstance(other, str):
             return other == self.name
         return NotImplemented
 
     def __neq__(self, other):
-        if isinstance(other, unicode):
+        if isinstance(other, str):
             return other != self.name
         return NotImplemented
 
@@ -73,14 +73,14 @@ class Contract(ChildSlither, SourceMapping):
         '''
             list(Structure): List of the structures
         '''
-        return self._structures.values()
+        return list(self._structures.values())
 
     def structures_as_dict(self):
         return self._structures
 
     @property
     def enums(self):
-        return self._enums.values()
+        return list(self._enums.values())
 
     def enums_as_dict(self):
         return self._enums
@@ -90,7 +90,7 @@ class Contract(ChildSlither, SourceMapping):
         '''
             list(Modifier): List of the modifiers
         '''
-        return self._modifiers.values()
+        return list(self._modifiers.values())
 
     def modifiers_as_dict(self):
         return self._modifiers
@@ -100,7 +100,7 @@ class Contract(ChildSlither, SourceMapping):
         '''
             list(Function): List of the functions
         '''
-        return self._functions.values()
+        return list(self._functions.values())
 
     @property
     def functions_inherited(self):
@@ -114,12 +114,11 @@ class Contract(ChildSlither, SourceMapping):
         '''
             list(Function): List of functions reachable from the contract (include super)
         '''
-        all_calls = [f.all_calls() for f in self.functions]
+        all_calls = (f.all_calls() for f in self.functions)
         all_calls = [item for sublist in all_calls for item in sublist] + self.functions
-        all_calls = list(set(all_calls))
+        all_calls = set(all_calls)
         return [c for c in all_calls if isinstance(c, Function)]
 
-
     def functions_as_dict(self):
         return self._functions
 
@@ -128,7 +127,7 @@ class Contract(ChildSlither, SourceMapping):
         '''
             list(Event): List of the events
         '''
-        return self._events.values()
+        return list(self._events.values())
 
     def events_as_dict(self):
         return self._events
@@ -138,7 +137,7 @@ class Contract(ChildSlither, SourceMapping):
         '''
             list(StateVariable): List of the state variables. 
         '''
-        return self._variables.values()
+        return list(self._variables.values())
 
     @property
     def variables(self):

slither/core/declarations/function.py

@@ -155,7 +155,7 @@ class Function(ChildContract, SourceMapping):
             Return all local variables
             Include paramters and return values
         """
-        return self._variables.values()
+        return list(self._variables.values())
 
     def variables_as_dict(self):
         return self._variables
@@ -275,7 +275,7 @@ class Function(ChildContract, SourceMapping):
         """
         write_var = [x.variables_written_as_expression for x in self.nodes]
         write_var = [x for x in write_var if x]
-        write_var = [item for sublist in write_var for item in sublist ]
+        write_var = [item for sublist in write_var for item in sublist]
         write_var = list(set(write_var))
         # Remove dupplicate if they share the same string representation
         write_var = [next(obj) for i, obj in groupby(sorted(write_var, key=lambda x: str(x)), lambda x: str(x))]
@@ -283,7 +283,7 @@ class Function(ChildContract, SourceMapping):
 
         write_var = [x.variables_written for x in self.nodes]
         write_var = [x for x in write_var if x]
-        write_var = [item for sublist in write_var for item in sublist ]
+        write_var = [item for sublist in write_var for item in sublist]
         write_var = list(set(write_var))
         # Remove dupplicate if they share the same string representation
         write_var = [next(obj) for i, obj in\

slither/core/declarations/modifier.py

@@ -1,7 +1,7 @@
 """
     Modifier module
 """
-from function import Function
+from .function import Function
 
 class Modifier(Function): pass
 

slither/core/declarations/solidityVariables.py

@@ -7,7 +7,7 @@ SOLIDITY_VARIABLES_COMPOSED = ["block.coinbase", "block.difficulty", "block.gasl
 
 SOLIDITY_FUNCTIONS = ["gasleft()", "assert(bool)", "require(bool)", "require(bool,string)", "revert()", "revert(string)", "addmod(uint256,uint256,uint256)", "mulmod(uint256,uint256,uint256)", "keccak256()", "sha256()", "sha3()", "ripemd160()", "ecrecover(bytes32,uint8,bytes32,bytes32)", "selfdestruct(address)", "suicide(address)", "log0(bytes32)", "log1(bytes32,bytes32)", "log2(bytes32,bytes32,bytes32)", "log3(bytes32,bytes32,bytes32,bytes32)", "blockhash(uint256)"]
 
-class SolidityVariable(object):
+class SolidityVariable:
 
     def __init__(self, name):
         assert name in SOLIDITY_VARIABLES
@@ -34,7 +34,7 @@ class SolidityVariableComposed(SolidityVariable):
 
 
 
-class SolidityFunction(object):
+class SolidityFunction:
 
     def __init__(self, name):
         assert name in SOLIDITY_FUNCTIONS

slither/core/expressions/assignmentOperation.py

@@ -5,7 +5,7 @@ from slither.core.expressions.expression import Expression
 
 logger = logging.getLogger("AssignmentOperation")
 
-class AssignmentOperationType(object):
+class AssignmentOperationType:
     ASSIGN =                0 # =
     ASSIGN_OR =             1 # |=
     ASSIGN_CARET =          2 # ^=

slither/core/expressions/binaryOperation.py

@@ -5,7 +5,7 @@ from slither.core.expressions.expression import Expression
 
 logger = logging.getLogger("BinaryOperation")
 
-class BinaryOperationType(object):
+class BinaryOperationType:
     POWER =             0 # **
     MULTIPLICATION =    1 # *
     DIVISION =          2 # /

slither/core/expressions/conditionalExpression.py

@@ -1,4 +1,4 @@
-from expression import Expression
+from .expression import Expression
 
 class ConditionalExpression(Expression):
 

slither/core/expressions/expressionTyped.py

@@ -1,5 +1,5 @@
 
-from expression import Expression
+from .expression import Expression
 
 class ExpressionTyped(Expression):
 

slither/core/expressions/literal.py

@@ -12,7 +12,4 @@ class Literal(Expression):
 
     def __str__(self):
         # be sure to handle any character
-        if isinstance(self._value, unicode):
-            return self._value.encode('utf-8')
         return str(self._value)
-

slither/core/expressions/newArray.py

@@ -1,5 +1,5 @@
 import logging
-from expression import Expression
+from .expression import Expression
 from slither.core.solidityTypes.type import Type
 
 logger = logging.getLogger("NewArray")

slither/core/expressions/newContract.py

@@ -1,4 +1,4 @@
-from expression import Expression
+from .expression import Expression
 
 class NewContract(Expression):
 

slither/core/expressions/unaryOperation.py

@@ -5,7 +5,7 @@ from slither.core.solidityTypes.type import Type
 
 logger = logging.getLogger("UnaryOperation")
 
-class UnaryOperationType(object):
+class UnaryOperationType:
     BANG =              0 # ! 
     TILD =              1 # ~ 
     DELETE =            2 # delete

slither/core/slitherCore.py

@@ -3,7 +3,7 @@
 """
 import os
 
-class Slither(object):
+class Slither:
     """
     Slither static analyzer
     """
@@ -18,13 +18,13 @@ class Slither(object):
     @property
     def contracts(self):
         """list(Contract): List of contracts."""
-        return self._contracts.values()
+        return list(self._contracts.values())
 
     @property
     def contracts_derived(self):
         """list(Contract): List of contracts that are derived and not inherited."""
-        inheritances = [x.inheritances for x in self.contracts]
-        inheritances = [item for sublist in inheritances for item in sublist]
+        inheritances = (x.inheritances for x in self.contracts)
+        inheritances = (item for sublist in inheritances for item in sublist)
         return [c for c in self._contracts.values() if c not in inheritances]
 
     def contracts_as_dict(self):

slither/core/solidityTypes/elementaryType.py

@@ -12,8 +12,8 @@ Uint = ['uint', 'uint8', 'uint16', 'uint24', 'uint32', 'uint40', 'uint48', 'uint
 Byte = ['byte', 'bytes', 'bytes1', 'bytes2', 'bytes3', 'bytes4', 'bytes5', 'bytes6', 'bytes7', 'bytes8', 'bytes9', 'bytes10', 'bytes11', 'bytes12', 'bytes13', 'bytes14', 'bytes15', 'bytes16', 'bytes17', 'bytes18', 'bytes19', 'bytes20', 'bytes21', 'bytes22', 'bytes23', 'bytes24', 'bytes25', 'bytes26', 'bytes27', 'bytes28', 'bytes29', 'bytes30', 'bytes31', 'bytes32']
 
 # https://solidity.readthedocs.io/en/v0.4.24/types.html#fixed-point-numbers
-M = range(8, 257, 8)
-N = range(0, 81)
+M = list(range(8, 257, 8))
+N = list(range(0, 81))
 MN = list(itertools.product(M,N))
 
 Fixed = ['fixed{}x{}'.format(m,n) for (m,n) in MN] + ['fixed']

slither/core/variables/eventVariable.py

@@ -1,4 +1,4 @@
-from variable import Variable
+from .variable import Variable
 from slither.core.children.childEvent import ChildEvent
 
 class EventVariable(ChildEvent, Variable): pass

slither/core/variables/functionTypeVariable.py

@@ -6,7 +6,7 @@
     }
 """
 
-from variable import Variable
+from .variable import Variable
 
 class FunctionTypeVariable(Variable): pass
 

slither/core/variables/localVariable.py

@@ -1,4 +1,4 @@
-from variable import Variable
+from .variable import Variable
 from slither.core.children.childFunction import ChildFunction
 
 class LocalVariable(ChildFunction, Variable): pass

slither/core/variables/stateVariable.py

@@ -1,4 +1,4 @@
-from variable import Variable
+from .variable import Variable
 from slither.core.children.childContract import ChildContract
 
 class StateVariable(ChildContract, Variable): pass

slither/core/variables/structureVariable.py

@@ -1,4 +1,4 @@
-from variable import Variable
+from .variable import Variable
 from slither.core.children.childStructure import ChildStructure
 
 class StructureVariable(ChildStructure, Variable): pass

slither/detectors/abstractDetector.py

@@ -6,9 +6,7 @@ from slither.utils.colors import green, yellow, red
 class IncorrectDetectorInitialization(Exception):
     pass
 
-class AbstractDetector(object):
-    __metaclass__ = abc.ABCMeta
-
+class AbstractDetector(object, metaclass=abc.ABCMeta):
     ARGUMENT = '' # run the detector with slither.py --ARGUMENT
     HELP = '' # help information
     CLASSIFICATION = None

slither/detectors/detectorClassification.py

@@ -1,4 +1,4 @@
-class DetectorClassification(object):
+class DetectorClassification:
     LOW = 0
     MEDIUM = 1
     HIGH = 2

slither/detectors/detectors.py

@@ -13,7 +13,7 @@ from slither.detectors.variables.uninitializedStateVarsDetection import Uninitia
 
 logger_detector = logging.getLogger("Detectors")
 
-class Detectors(object):
+class Detectors:
 
     def __init__(self):
         self.detectors = {}

slither/detectors/shadowing/shadowingFunctionsDetection.py

@@ -41,7 +41,7 @@ class ShadowingFunctionsDetection(AbstractDetector):
         for c in self.contracts:
             shadowing = self.detect_shadowing(c)
             if shadowing:
-                for contract, funcs in shadowing.iteritems():
+                for contract, funcs in shadowing.items():
                     results.append({'vuln':self.vuln_name,
                                     'filename': self.filename,
                                     'contractShadower': c.name,

slither/printers/abstractPrinter.py

@@ -3,9 +3,7 @@ import abc
 class IncorrectPrinterInitialization(Exception):
     pass
 
-class AbstractPrinter(object):
-    __metaclass__ = abc.ABCMeta
-
+class AbstractPrinter(object, metaclass=abc.ABCMeta):
     ARGUMENT = '' # run the printer with slither.py --ARGUMENT
     HELP = '' # help information
 

slither/printers/printers.py

@@ -12,7 +12,7 @@ from slither.printers.functions.authorization import PrinterWrittenVariablesAndA
 
 logger_printer = logging.getLogger("Printers")
 
-class Printers(object):
+class Printers:
 
     def __init__(self):
         self.printers = {}

slither/printers/summary/printerSummary.py

@@ -14,7 +14,7 @@ class PrinterSummary(AbstractPrinter):
     def _convert(l):
         if l:
             n = 2
-            l = [l[i:i + n] for i in xrange(0, len(l), n)]
+            l = [l[i:i + n] for i in range(0, len(l), n)]
             l = [str(x) for x in l]
             return "\n".join(l)
         return str(l)

slither/slither.py

@@ -1,14 +1,15 @@
+import os
 import sys
 import logging
 import subprocess
 
-import os.path
-from solcParsing.slitherSolc import SlitherSolc
-from utils.colors import red
+from .solcParsing.slitherSolc import SlitherSolc
+from .utils.colors import red
 
 logger = logging.getLogger("Slither")
 logging.basicConfig()
 
+
 class Slither(SlitherSolc):
 
     def __init__(self, filename, solc='solc', disable_solc_warnings=False ,solc_arguments=''):
@@ -24,8 +25,8 @@ class Slither(SlitherSolc):
 
         if is_ast_file:
             with open(filename) as astFile:
-                data = astFile.read()
-                if not data:
+                stdout = astFile.read()
+                if not stdout:
                     logger.info('Empty AST file: %s', filename)
                     sys.exit(-1)
         else:
@@ -44,20 +45,22 @@ class Slither(SlitherSolc):
             # Add . as default allowed path
             if '--allow-paths' not in cmd:
                 cmd += ['--allow-paths', '.']
+
             process = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-            data, err = process.communicate()
 
-            if err and (not disable_solc_warnings):
-                err = err.split('\n')
-                err = [x if 'Error' not in x else red(x) for x in err]
-                err = '\n'.join(err)
-                logger.info('Compilation warnings/errors on %s:\n%s', filename, err)
+            stdout, stderr = process.communicate()
+            stdout, stderr = stdout.decode(), stderr.decode()  # convert bytestrings to unicode strings
 
+            if stderr and (not disable_solc_warnings):
+                stderr = stderr.split('\n')
+                stderr = [x if 'Error' not in x else red(x) for x in stderr]
+                stderr = '\n'.join(stderr)
+                logger.info('Compilation warnings/errors on %s:\n%s', filename, stderr)
 
-        data = data.split('\n=')
+        stdout = stdout.split('\n=')
 
         super(Slither, self).__init__(filename)
-        for d in data:
+        for d in stdout:
             self.parse_contracts_from_json(d)
 
         self.analyze_contracts()

slither/solcParsing/declarations/contractSolc04.py

@@ -233,7 +233,7 @@ class ContractSolc04(Contract):
 
     def analyze_params_functions(self):
         for father in self.inheritances_reverse:
-            functions = {k:v for (k,v) in father.functions_as_dict().iteritems()} #if not v.is_constructor}
+            functions = {k:v for (k,v) in father.functions_as_dict().items()} #if not v.is_constructor}
             self._functions.update(functions)
 
         for function in self._functions_no_params:
@@ -251,3 +251,6 @@ class ContractSolc04(Contract):
         for function in self.functions:
             function.analyze_content()
         return
+
+    def __hash__(self):
+        return self._id

slither/solcParsing/solidityTypes/typeParsing.py

@@ -17,7 +17,7 @@ import re
 
 logger = logging.getLogger('TypeParsing')
 
-class UnknownType(object):
+class UnknownType:
     def __init__(self, name):
         self._name = name
 

slither/solcParsing/variables/eventVariableSolc.py

@@ -1,5 +1,5 @@
 
-from variableDeclarationSolc import VariableDeclarationSolc
+from .variableDeclarationSolc import VariableDeclarationSolc
 from slither.core.variables.eventVariable import EventVariable
 
 class EventVariableSolc(VariableDeclarationSolc, EventVariable): pass

slither/solcParsing/variables/localVariableInitFromTupleSolc.py

@@ -1,5 +1,5 @@
 
-from variableDeclarationSolc import VariableDeclarationSolc
+from .variableDeclarationSolc import VariableDeclarationSolc
 from slither.core.variables.localVariableInitFromTuple import LocalVariableInitFromTuple
 
 class LocalVariableInitFromTupleSolc(VariableDeclarationSolc, LocalVariableInitFromTuple):

slither/solcParsing/variables/localVariableSolc.py

@@ -1,5 +1,5 @@
 
-from variableDeclarationSolc import VariableDeclarationSolc
+from .variableDeclarationSolc import VariableDeclarationSolc
 from slither.core.variables.localVariable import LocalVariable
 
 class LocalVariableSolc(VariableDeclarationSolc, LocalVariable): pass

slither/solcParsing/variables/stateVariableSolc.py

@@ -1,5 +1,5 @@
 
-from variableDeclarationSolc import VariableDeclarationSolc
+from .variableDeclarationSolc import VariableDeclarationSolc
 from slither.core.variables.stateVariable import StateVariable
 
 class StateVariableSolc(VariableDeclarationSolc, StateVariable): pass

slither/solcParsing/variables/structureVariableSolc.py

@@ -1,5 +1,5 @@
 
-from variableDeclarationSolc import VariableDeclarationSolc
+from .variableDeclarationSolc import VariableDeclarationSolc
 from slither.core.variables.structureVariable import StructureVariable
 
 class StructureVariableSolc(VariableDeclarationSolc, StructureVariable): pass

slither/visitors/expression/expression.py

@@ -18,7 +18,7 @@ from slither.core.expressions.unaryOperation import UnaryOperation
 
 logger = logging.getLogger("ExpressionVisitor")
 
-class ExpressionVisitor(object):
+class ExpressionVisitor:
 
     def __init__(self, expression):
         self._expression = expression