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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 rate_limit_wait(self):
 """ Sleep if rate limiting is required based on current time and last query. """

        if self._rate_limit_dt and self._last_query is not None:
            dt = time.time() - self._last_query
            wait = self._rate_limit_dt - dt
            if wait > 0:
                time.sleep(wait)