def write_command(self, request_id, msg):
        """Send "insert" etc. command, returning response as a dict.

        Can raise ConnectionFailure or OperationFailure.

        :Parameters:
          - `request_id`: an int.
          - `msg`: bytes, the command message.
        """
        self.send_message(msg, 0)
        reply = self.receive_message(request_id)
        result = reply.command_response()

        # Raises NotMasterError or OperationFailure.
        helpers._check_command_response(result)
        return result
Send "insert" etc. command, returning response as a dict.

        Can raise ConnectionFailure or OperationFailure.

        :Parameters:
          - `request_id`: an int.
          - `msg`: bytes, the command message.
        
stackoverflow/venv/lib/python3.6/site-packages/pymongo/pool.py