Eliot Miranda wrote:

> I think just
> 
> True>>xor: aBoolean
>     ^aBoolean not
> 
> False>>xor: aBoolean
>     ^aBoolean

<OT>
One of my first excerices in Smalltalk was to implement an exclusive or 
as "||", without being told that xor: is exactly that.
The reference implementation was the above, if memory serves me right.
</OT>

Sorry for reminiscing in public...