Remove optional ERC20 functions

slither/core/declarations/contract.py

@@ -647,8 +647,7 @@ class Contract(ChildSlither, SourceMapping):
         """
         # We do not check for all the functions, as name(), symbol(), might give too many FPs
         full_names = self.functions_signatures
-        return ('approve(address,uint256)' in full_names or
+        return ('ownerOf(uint256)' in full_names or
-                'ownerOf(uint256)' in full_names or
                 'safeTransferFrom(address,address,uint256,bytes)' in full_names or
                 'safeTransferFrom(address,address,uint256)' in full_names or
                 'setApprovalForAll(address,bool)' in full_names or

slither/utils/erc.py

@@ -5,10 +5,8 @@ def erc_to_signatures(erc):
 
 # Final
 # https://eips.ethereum.org/EIPS/eip-20
-ERC20 = [('name', [], 'string'),
+# name, symbolc, decimals are optionals
-         ('symbol', [], 'string'),
+ERC20 = [('totalSupply', [], 'uint256'),
-         ('decimals', [], 'uint8'),
-         ('totalSupply', [], 'uint256'),
          ('balanceOf', ['address'], 'uint256'),
          ('transfer', ['address', 'uint256'], 'bool'),
          ('transferFrom', ['address', 'address', 'uint256'], 'bool'),