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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add_ephemeral_listener(self, callback, event_type=None):
 """Add a callback handler for ephemeral events going to this room. Args: callback (func(room, event)):
 Callback called when an ephemeral event arrives. event_type (str):
 The event_type to filter for. Returns: uuid.UUID: Unique id of the listener, can be used to identify the listener. """

        listener_id = uuid4()
        self.ephemeral_listeners.append(
            {
                'uid': listener_id,
                'callback': callback,
                'event_type': event_type
            }
        )
        return listener_id