(self, listener: UserListener)
return listener in self.__listeners
Return true if listener is subscribed to this topic.
Return true if listener is subscribed to this topic.
Return true if listener is subscribed to this topic .
def hasListener(self, listener: UserListener) -> bool:
        """Return true if listener is subscribed to this topic."""
        return listener in self.__listeners
def hasListener ( self , listener : UserListener ) -> bool : return listener in self . __listeners