#1755097: document default values for [].sort() and sorted().
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index e153bc8..6720f19 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -1038,10 +1038,11 @@
*cmp* specifies a custom comparison function of two arguments (iterable
elements) which should return a negative, zero or positive number depending on
whether the first argument is considered smaller than, equal to, or larger than
- the second argument: ``cmp=lambda x,y: cmp(x.lower(), y.lower())``
+ the second argument: ``cmp=lambda x,y: cmp(x.lower(), y.lower())``. The default
+ value is ``None``.
*key* specifies a function of one argument that is used to extract a comparison
- key from each list element: ``key=str.lower``
+ key from each list element: ``key=str.lower``. The default value is ``None``.
*reverse* is a boolean value. If set to ``True``, then the list elements are
sorted as if each comparison were reversed.