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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 switch(self, value=None):
 """Switch back to the origin fiber. The fiber is switch in next time the event loop runs."""

        if self._hub is None or not self._fiber.is_alive():
            return
        self._hub.run_callback(self._fiber.switch, value)
        self._hub = self._fiber = None