Proposal: allow '?' and '!' in identifiers

[Joshua Marshall]

Christoph Horst <rc-bashar at gmx.net> wrote:
> Nathaniel Gray <n8gray at caltech.edu.is.my.email.address> wrote:
>>IMHO it's not worth adding "!", but if "?" doesn't break anything then it's 
>>a net gain.  I assert that it _would_ make Python more expressive to add an 
>>elegant way of indicating that a function returns only boolean values.

> What's wrong with prefixing the function name with 'is'?

I wouldn't say anything is wrong with that approach.  But then I could
also ask "Why do we need underscores as valid identifier characters?
You can just capitalize the next letter."
The question mark is an unused character, and carries some
natural-language meaning.  It's useful.