Fix parameter names in assertIn() docs (GH-18829)

The names "member" and "container" for the arguments are also used in the module and shown with the help() function, and are immediately understandable in this context, contrary to "first" and "second".
(cherry picked from commit a388bbd3f129364c39843f63e92f08bc53c71905)

Co-authored-by: Christoph Zwerschke <cito@online.de>

diff --git a/Doc/library/unittest.rst b/Doc/library/unittest.rst
index 0cd6918b1d2533d0985a5fd915886e1db5c8b74c..3cc0665d00b03b58dfeb86dbca4ad3af5ffd5b72 100644 (file)
--- a/Doc/library/unittest.rst
+++ b/Doc/library/unittest.rst
@@ -910,10 +910,10 @@ Test cases
       .. versionadded:: 3.1
 
 
-   .. method:: assertIn(first, second, msg=None)
-               assertNotIn(first, second, msg=None)
+   .. method:: assertIn(member, container, msg=None)
+               assertNotIn(member, container, msg=None)
 
-      Test that *first* is (or is not) in *second*.
+      Test that *member* is (or is not) in *container*.
 
       .. versionadded:: 3.1