Removes a send_last_message function previously registered
        with the Dispatcher.

        Args:
            connection (str): A locally unique identifier provided
                by the receiver of messages.

def remove_send_last_message(self, connection):
        """Removes a send_last_message function previously registered
        with the Dispatcher.

        Args:
            connection (str): A locally unique identifier provided
                by the receiver of messages.
        """
        if connection in self._send_last_message:
            del self._send_last_message[connection]
            LOGGER.debug("Removed send_last_message function "
                         "for connection %s", connection)
        else:
            LOGGER.warning("Attempted to remove send_last_message "
                           "function for connection %s, but no "
                           "send_last_message function was registered",
                           connection)