From: "christophe.poucet@..." <christophe.poucet@...>
Date: 2005-09-22T21:31:39+09:00
Subject: Re: Set#== ain't..

The above solution of set.all? {|x| any? { |y| x== y} } is not a full
solution.  This will only work if you have set-nesting as described in
the original problem, but not if you have higher nesting (because then
you run back into the same original problem except one nesting level
down).

If this was the actual definition of ==, then it would work of course
:).