Moshe Zadka <mzadka@geocities.com>:

Update the "in" / "not in" description to accomodate the current use
of the __contains__() discipline.  This patch also incorporates
suggestions from Marc-Andre Lemburg <mal@lemburg.com>, minor markup
revisions from Fred Drake, and some rewording of the first affected
paragraph (also from Fred).

Closes SourceForge patch #100831.