From: Raymond Hettinger Date: Tue, 26 Apr 2016 07:59:16 +0000 (-0700) Subject: Issue #23986: Note that the in-operator for lists and tuples check identity before... X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=167c81d5ed5a56a6f05a0786db483b2b73a55a45;p=python Issue #23986: Note that the in-operator for lists and tuples check identity before equality. --- diff --git a/Doc/reference/expressions.rst b/Doc/reference/expressions.rst index 1fd37f3bb3..c46ab64585 100644 --- a/Doc/reference/expressions.rst +++ b/Doc/reference/expressions.rst @@ -1153,7 +1153,7 @@ types to support membership tests without being a sequence. In particular, dictionaries (for keys) and sets support membership testing. For the list and tuple types, ``x in y`` is true if and only if there exists an -index *i* such that ``x == y[i]`` is true. +index *i* such that either ``x is y[i]`` or ``x == y[i]`` is true. For the Unicode and string types, ``x in y`` is true if and only if *x* is a substring of *y*. An equivalent test is ``y.find(x) != -1``. Note, *x* and *y*