NotImplementedError returned instead of raised

[dacevedo12]

There are some functions like from_native in the VersionRange base class that return this exception instead of raising it.

This leads to a TypeError when using it as version in version_range.from_native(...), effectively attempting __contains__ over an exception class

Is this intended?

[pombredanne]

Is this intended?

It used to be a common idiom pre-typing, but it really does not matter. Raising is fine as the intention is to signal loudly that a base method is not implemented