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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 _pushx(self, command, *args, **kwargs):
 """ Helper for lpushx and rpushx, that only index the new values if the list existed when the command was called """

        result = self._traverse_command(command, *args, **kwargs)
        if self.indexable and result:
            self.index(args)
        return result