code: def remove_listener(self, registration_id):
          
          try:
              self._listeners.pop(registration_id)
              return True
          except KeyError:
              return False
docs: Removes a lifecycle listener.
  
          :param registration_id: (str), the id of the listener to be removed.
          :return: (bool), ``true`` if the listener is removed successfully, ``false`` otherwise.