[Python-ideas] Make it optional

[anatoly techtonik]

Flexibility of something is the fact that you are not forced
to use it in some unnatural way. I'd say that most PEPs
related to core Python are flexible, but I am not sure about
the rest.

PEPs are made to resolve ambiguities. But it doesn't mean
limiting flexibility and setting hard limitation. What is hard
limitation standard? For example, marking version you can
not parse as pre-release. PIP actually does this, which
prevents all packages with versions that are not comply with
"versioning PEP" from installing.

"pre-release" is a feature. Inflexible, tempting to guess,
getting in a way, implicit and confusing. I just filled three or
four bugs about it. How come that it appeared at all? Well,
because it is useful. In some cases. But the problem is that
it affects you even if you don't need it.

"Make it optional" is a very good principle for those cases
when you can not predict how users are going to use your
feature and if they need it at all.
-- 
anatoly t.