code: def close(self):
          '''Close all the connections and clean up.
  
          This instance will not be usable after calling this method.
          '''
          for key, pool in tuple(self._host_pools.items()):
              pool.close()
  
              del self._host_pools[key]
              del self._host_pool_waiters[key]
  
          self._closed = Truf close(self):
          '''Close all the connections and clean up.
  
          This instance will not be usable after calling this method.
          '''
          for key, pool in tuple(self._host_pools.items()):
              pool.close()
  
              del self._host_pools[key]
              del self._host_pool_waiters[key]
  
          self._closed = True
docs: Close all the connections and clean up.
  
          This instance will not be usable after calling this method.