Another conditional expression candidate (PEP 308)

[Paul Rubin]

Andrew Koenig <ark at research.att.com> writes:
> Roy> If "else: pass" isn't required in the statement, why should
> Roy> "else: None" be required in the expression?
> 
> Because "pass" is obviously the only sensible default behavior for
> statements, but None is not obviously the only sensible default value
> for conditional expressions.

Again looking at the Lisp precedent, (cond (x y)) gives nil if x is
false, and that seems to have worked out.  So I'm ok with making the
else optional.  I'm also ok with making it mandatory.