The PEP should clarify the status of typing vs. types

[gvanrossum]

Lukasz wrote:

• The remark about removing types from being mentioned actually
  makes me think we could solve many issues before they arise by
  introducing a short section The place of the typing module in
  the standard library which would explain how the authors intend for
  it to be used and what is its role compared to builtin types,
  types, collections, and collections.abc. The worries
  that Guido has about the types module being ill-suited for type
  hinted are spot on, we should mention that in the document.

[ambv]

Ignored this issue for now: don't know yet.

[gvanrossum]

Isn't this all pretty clear now? We should just downplay types.py -- it only defines concrete types. But we could easily have a stub for it if mypy has trouble understanding its highly dynamic approach.

[gvanrossum]

I think we need no more edits for this topic. typing is mentioned exactly once and in an appropriate fashion (types defined there are acceptable). (@jukka -- is there mypy work needed to implement this?)