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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_done_callback(self, future, callback):
 """ Add a callback on a future object put here so it can be implemented with different event loops. Parameters future: Future or Deferred Future implementation for the current EventLoop callback: callable Callback to invoke when the future is done """

        if future is None:
            raise bridge.BridgeReferenceError(
                "Tried to add a callback to a nonexistent Future. "
                "Make sure you pass the `returns` argument to your JavaMethod")
        return self.loop.add_done_callback(future, callback)