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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 disconnect(self, callback):
 """ Disconnects a callback from this signal. :param callback: The callback to disconnect. :param weak: A flag that must have the same value than the one specified during the call to `connect`. .. warning:: If the callback is not connected at the time of call, a :class:`ValueError` exception is thrown. .. note:: You may call `disconnect` from a connected callback. """

        try:
            self._callbacks.remove(callback)
        except ValueError:
            self._callbacks.remove(ref(callback))