code: def release(self, connection: Connection):
          '''Put a connection back in the pool.
  
          Coroutine.
          '''
          assert not self._closed
  
          key = connection.key
          host_pool = self._host_pools[key]
  
          _logger.debug('Check in %s', key)
  
          yield from host_pool.release(connection)
  
          force = self.count() > self._max_count
          yield from self.clean(force=forcef release(self, connection: Connection):
          '''Put a connection back in the pool.
  
          Coroutine.
          '''
          assert not self._closed
  
          key = connection.key
          host_pool = self._host_pools[key]
  
          _logger.debug('Check in %s', key)
  
          yield from host_pool.release(connection)
  
          force = self.count() > self._max_count
          yield from self.clean(force=force)
docs: Put a connection back in the pool.
  
          Coroutine.