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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 close(self):
 """ Iterate through all of the connections and close each one. """

        if not self._closed:
            self._closed = True
            self._stop_multi_pools()
            if self._http_pool is not None:
                self._http_pool.clear()
                self._http_pool = None
            if self._tcp_pool is not None:
                self._tcp_pool.clear()
                self._tcp_pool = None