<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def throw(self, typ, val=None, tb=None):
 """Throw an exception into the origin fiber. The exception is thrown the next time the event loop runs."""

        # The might seem redundant with self._fiber.cancel(exc), but it isn't
        # as self._fiber might be a "raw" fibers.Fiber() that doesn't have a
        # cancel() method.
        if self._hub is None or not self._fiber.is_alive():
            return
        self._hub.run_callback(self._fiber.throw, typ, val, tb)
        self._hub = self._fiber = None