Remove all legacy future imports.
Review Request #12644 — Created Sept. 25, 2022 and submitted — Latest diff uploaded
This removes the
imports, which are no longer needed with Python 3.
Some of the affected modules have had new docstrings added, or updated
for consistency. Most of these are command or utility docs. None of the
API docs have been updated, since that work is being handled separately.
All unit tests pass.