Can one of you CS wizzes point me at the best way to
maintain a set of sets where all elements of all sets
must be unique? I don't need a really big data set
but rolling my own with the list module feels wrong.
For example {{1,2,3},{4,5,6},{7,8,9}} is a valid set.
Trying to enter {9,10,11} should fail.
-Vance