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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 _get_more(self):
 """Initial query or getMore. Returns a Future."""

        if not self.alive:
            raise pymongo.errors.InvalidOperation(
                "Can't call get_more() on a MotorCursor that has been"
                " exhausted or killed.")

        self.started = True
        return self._refresh()