code: def copy(self, key=None):
          
          other = self.__class__(
              self.__iter__(),
              self.maxlen,
              redis=self.redis,
              key=key,
              writeback=self.writeback,
          )
  
          return other
docs: Return a new collection with the same items as this one.
          If *key* is specified, create the new collection with the given
          Redis key.