code: def get_invalid_txn_info(self, batch_id):
          
          with self._lock:
              return [info.copy() for info in self._invalid.get(batch_id, [])]
docs: Fetches the id of the Transaction that failed within a particular
          Batch, as well as any error message or other data about the failure.
  
          Args:
              batch_id (str): The id of the Batch containing an invalid txn
  
          Returns:
              list of dict: A list of dicts with three possible keys:
                  * 'id' - the header_signature of the invalid Transaction
                  * 'message' - the error message sent by the TP
                  * 'extended_data' - any additional data sent by the TP