code: def solidity_get_contract_key(all_contracts, filepath, contract_name):
      
      if contract_name in all_contracts:
          return contract_name
      else:
          if filepath is None:
              filename = '<stdin>'
          else:
              _, filename = os.path.split(filepath)
          contract_key = filename + ":" + contract_name
          return contract_key if contract_key in all_contracts else None
docs: A backwards compatible method of getting the key to the all_contracts
      dictionary for a particular contract