code: def add_listener(self, on_lifecycle_change):
          
          id = str(uuid.uuid4())
          self._listeners[id] = on_lifecycle_change
          return id
docs: Add a listener object to listen for lifecycle events.
  
          :param on_lifecycle_change: (Function), function to be called when LifeCycle state is changed.
          :return: (str), id of the listener.