code: def get_token_network(
              self,
              token_address: TokenAddress,
              block_identifier: BlockSpecification = 'latest',
      ) -> Optional[Address]:
          
          if not isinstance(token_address, T_TargetAddress):
              raise ValueError('token_address must be an address')
  
          address = self.proxy.contract.functions.token_to_token_networks(
              to_checksum_address(token_address),
          ).call(block_identifier=block_identifier)
          address = to_canonical_address(address)
  
          if is_same_address(address, NULL_ADDRESS):
              return None
  
          return address
docs: Return the token network address for the given token or None if
          there is no correspoding address.