[jmcdonald-ut]

He addresses this in his post.

  if x.in? my_set   # very ugly

With that said, I personally don't agree with the post.

[bhaak]

I don't know what's so ugly about this.

I wouldn't call the method "in?" but maybe "element_of?" or "member_of?" but besides that, I don't see the need for an operator.