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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 run(self, message_cb):
 """Run the event loop to receive messages from Nvim. While the event loop is running, `message_cb` will be called whenever a message has been successfully parsed from the input stream. """

        self._message_cb = message_cb
        self.loop.run(self._on_data)
        self._message_cb = None