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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 _on_server_disconnect(self, exception):
 """Handle server disconnection."""

        self._protocol = None
        if self._on_disconnect_callback_func and callable(self._on_disconnect_callback_func):
            self._on_disconnect_callback_func(exception)
        if self._reconnect:
            self._reconnect_cb()