Feasible Idea?: Range Tester

[timotheecour]

> it would have to be agreed upon
> whether assertions should be used or whether RangeError should 
> be used (or
> that using either was valid, though that's a bad idea IMHO).

if we force range code to throw RangeError, wouldn't that prevent 
optimization in release mode? If so, that's no good. Also, simply 
using assert(...); is much more convenient in lots of cases 
(think user written ranges that don't wanna be bogged down by 
boilerplate).
So why not just say: only AssertError or RangeError are valid in 
that case, that doesn't seem controversial.