code: def get_server(self, key, **kwds):
          
          kwds = dict(self.kwds, **kwds)
          server = self.servers.get(key)
          if server:
              # Make sure it's the right server.
              server.check_keywords(self.constructor, kwds)
          else:
              # Make a new server
              server = _CachedServer(self.constructor, key, kwds)
              self.servers[key] = server
  
          return server
docs: Get a new or existing server for this key.
  
          :param int key: key for the server to use