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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 _remove(self, xer, primary):
 """ Private method for removing a descriptor from the event loop. It does the inverse job of _add, and also add a check in case of the fd has gone away. """

        if xer in primary:
            notifier = primary.pop(xer)
            notifier.shutdown()