Patch by Emily Morehouse.

Original patch by James Edwards.

Patch by TAKASE Arihiro.

Patch by Martin Panter.

Patch by James Edwards.

Add an entry in the language datamodel special methods section.
Revise and index its discussion in the stdtypes mapping/dict section.

Patch by Chaitanya Agrawal.

Patch by Steve Dougherty.

(Contributed by Feliks Kluzniak.)

Initial patch by Nick Coghlan

Patch by Priya Pappachan, based on suggestions from Terry Reedy
and myself.

See issues #7994 and #9856.  I also modified with wording of the format doc
entry to better match what really happens, and added a versionchanged to the
datamodel object.__format__ section.

Patch from Claudiu Popa.

Issue #17934: Add a clear() method to frame objects, to help clean up expensive details (local variables) and break reference cycles.

  object's custom `__hash__()` method.

Closes #4159: add LaTeX tabular column specifications to tables that otherwise are cut off or have overlapping text.

This commit also moves the documentation for the str built-in function to
the new class entry.  Links to :class:`str` now go to the class entry with
the string methods immediately afterwards.