(self, event, subscriber, append=True)
Add a subscriber for an event.

        :param event: The name of an event.
        :param subscriber: The subscriber to be added (and called when the
                           event is published).
        :param append: Whether to append or prepend the subscriber to an
                       existing subscriber list for the event.
Add a subscriber for an event.
Add a subscriber for an event .
def add(self, event, subscriber, append=True):
        """
        Add a subscriber for an event.

        :param event: The name of an event.
        :param subscriber: The subscriber to be added (and called when the
                           event is published).
        :param append: Whether to append or prepend the subscriber to an
                       existing subscriber list for the event.
        """
        subs = self._subscribers
        if event not in subs:
            subs[event] = deque([subscriber])
        else:
            sq = subs[event]
            if append:
                sq.append(subscriber)
            else:
                sq.appendleft(subscriber)
def add ( self , event , subscriber , append = True ) : subs = self . _subscribers if event not in subs : subs [ event ] = deque ( [ subscriber ] ) else : sq = subs [ event ] if append : sq . append ( subscriber ) else : sq . appendleft ( subscriber )