Remove an unused early-out test from the critical path for
dict and set lookups.

When the strings already have matching lengths, kinds, and hashes,
there is no additional information gained by checking the first
characters (the probability of a mismatch is already known to
be less than 1 in 2**64).

prefix from two attributes and two methods of History class.

Issue #18680: JSONDecoder should document that it raises a ValueError
  for malformed data

docstrings and ValueError messages. Patch by Zhongyue Luo

now working with comment block selections. Patch was part of 18226 patch.

Move comment code to a separate function so it can be separately tested.
Original patches by Todd Rovito and Phil Webster.

Before this patch it would raise an error when trying to display
documentation for a method that used annotations.

Patch by Claudiu Popa.

Also, document the policy keyword that was added to Message in 3.3.

#18581: remove duplicate test and run a test class that was skipped.  Initial patch by Vajrasky Kok.

#18273: move the tests in Lib/test/json_tests to Lib/test/test_json and make them discoverable by unittest.  Patch by Zachary Ware.

Patch by Madison May.