clNub :: (Monad m, Eq a, Hashable a)
  => Conduit a m a
clNub = evalStateC HashSet.empty clNubState
clNub :: (Monad m, Eq a, Hashable a)
  => Conduit a m a
clNub = evalStateC HashSet.empty clNubState
clNub = evalStateC HashSet.empty clNubState