[Pharo-project] Boolean Logic

[Robert Sirois]

Ok, this may be from a simple lack of understanding, but I just have to know ;)
Why can I call #or: (Boolean and friends) with a block, but #xor: only takes a 
Boolean? I would think the paradigm would remain the same and be able to 
compose operators like #or:, etc.?
What am I missing? Thanks!
RS