bpo-32739: Show default value for rotate() (GH-5485) (GH-5514)

miss-islington · rhettinger · rhettinger · commit 52f745852e49 · 2018-02-03T09:08:42.000-08:00
(cherry picked from commit 589c718) Co-authored-by: Raymond Hettinger <rhettinger@users.noreply.github.com>
diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
@@ -509,11 +509,14 @@ or subtracting from an empty counter.
         .. versionadded:: 3.2
 
 
-    .. method:: rotate(n)
+    .. method:: rotate(n=1)
 
-        Rotate the deque *n* steps to the right.  If *n* is negative, rotate to
-        the left.  Rotating one step to the right is equivalent to:
-        ``d.appendleft(d.pop())``.
+        Rotate the deque *n* steps to the right.  If *n* is negative, rotate
+        to the left.
+
+        When the deque is empty, rotating one step to the right is equivalent
+        to ``d.appendleft(d.pop())``, and rotating one step to the left is
+        equivalent to ``d.append(d.popleft())``.
 
 
     Deque objects also provide one read-only attribute:
