Send the message to the observer.

        :param msg: the message to send
        :param frm: the name of the node which sent this `msg`

def send_to_observer(self, msg, frm):
        """
        Send the message to the observer.

        :param msg: the message to send
        :param frm: the name of the node which sent this `msg`
        """
        logger.debug("{} sending message to observer: {}".
                     format(self, (msg, frm)))
        self._observer.append_input(msg, frm)