code: def retrieve(self, txid, headers=None):
          
          path = self.path + txid
          return self.transport.forward_request(
              method='GET', path=path, headers=None)
docs: Retrieves the transaction with the given id.
  
          Args:
              txid (str): Id of the transaction to retrieve.
              headers (dict): Optional headers to pass to the request.
  
          Returns:
              dict: The transaction with the given id.