Would it be useful to have one Python source file with an OrderedDict of
(API_feat_lbl, [(start, None)]) mappings
and a lookup?

* [ ] feat/version segments/rays map
* [ ] .lookup("print[_function]")

Syntax ideas:

* has("print[_function]")

Advantages

* More pythonic to check for features than capabilities
* Forward maintainability

Disadvantages:

*

Alternatives:

* six, nine, future
* try/import ENOENT