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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 del_handler(self, handle):
 """ Remove the handle registered for `handle` :raises KeyError: The handle wasn't registered. """

        _, _, _, respondent = self._handle_map.pop(handle)
        if respondent:
            self._handles_by_respondent[respondent].discard(handle)