def close(self) -> None:
        """
        Close all pooled connections and disable the pool.
        """
        if self.pool is None:
            return
        # Disable access to the pool
        old_pool, self.pool = self.pool, None

        # Close all the HTTPConnections in the pool.
        _close_pool_connections(old_pool)

        Close all pooled connections and disable the pool.
        
src/urllib3/connectionpool.py