code: def subscribe(self, receiver):
          "Subscribes an external handler to this channel."
          log.debug('{0}.{1} subscribe to {2}'
                    .format(receiver.__module__, receiver.__name__, self))
          self.signal.connect(receiverf subscribe(self, receiver):
          "Subscribes an external handler to this channel."
          log.debug('{0}.{1} subscribe to {2}'
                    .format(receiver.__module__, receiver.__name__, self))
          self.signal.connect(receiver)
docs: Subscribes an external handler to this channel.