Clarify "cardinality of" as "number of elements in" as many readers do

gpshead · gpshead · commit e27403b75f4c · 2016-02-08T09:58:40.000-08:00
not have a math vocabulary.
diff --git a/Doc/library/stdtypes.rst b/Doc/library/stdtypes.rst
@@ -3828,7 +3828,7 @@ The constructors for both classes work the same:
 
    .. describe:: len(s)
 
-      Return the cardinality of set *s*.
+      Return the number of elements in set *s* (cardinality of *s*).
 
    .. describe:: x in s
 
