code: def clean(self):
          
          LOGGER.debug('Cleaning the pool')
          for connection in [self.connections[k] for k in self.connections if
                             self.connections[k].closed]:
              LOGGER.debug('Removing %s', connection.id)
              self.remove(connection.handle)
  
          if self.idle_duration > self.idle_ttl:
              self.close()
  
          LOGGER.debug('Pool %s cleaned', self.id)
docs: Clean the pool by removing any closed connections and if the pool's
          idle has exceeded its idle TTL, remove all connections.