Found by Coverity.

Break up the 'someos' docs classification based on a more user-focused scheme, including creation of a separate 'Concurrent Execution' section

s/path importer/path based finder/ (because the path based finder is not an importer and the simpler 'path finder' is too ambiguous)

Close #14814: Avoid depending on struct by using newer features. Also use enumerate where appropriate (patch by Serhiy Storchaka). Declaring PEP 3144 final at this point - any further changes to code or docs can go in new issues.

Issue #14814: document the Interface APIs and fix various problems with the string representations (initial patch by Eli Bendersky).

Patch by Francisco Martín Brugué.

Patch by Francisco Martín Brugué.

for certain locales (utf-16 and utf-32 family).

Patch by Chris Jerdonek.

for certain locales (utf-16 and utf-32 family).

Patch by Chris Jerdonek.

Patch by Kushal Das.

Patch by Kushal Das.

Patch by Chris Jerdonek.

Patch by Chris Jerdonek.

This is analogous to the link for `flie objects` in the description of
'open' that exists in the 2.7 docs, and adds a similar link to the
io docs.

Patch by Chris Jerdonek.