> The other classes in the image that do this are:
> 
> TextLine
> LargePositiveInteger

[snip]

> To be fair, it is doubtful that most of these would actually be used as 
> Set or Dictionary keys, but one can certainly imagine uses for some of 
> them (LargePositiveInteger, SequenceableCollection).  I guess this should 
> be added to the official "cleanup list" of things to fix.

Fortunately, LargePositiveInteger DOES maintain the hash invariant.
I'm sure there is a lot of code out there the uses LargeIntegers.

I didn't check any of the SequencableCollection subclasses, but I find
it hard to believe that All of them also don't work right.

-- Mike Klein