Add doctest and improve readability for move_to_end() example. (#30370)

diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index 8bf3cb6cb12da17cac0b0b792b5b8f3202f7027e..b8a717d883c0931fe1dca38d8e19071adb82d4b0 100644 (file)
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -1120,14 +1120,16 @@ Some differences from :class:`dict` still remain:
         Move an existing *key* to either end of an ordered dictionary.  The item
         is moved to the right end if *last* is true (the default) or to the
         beginning if *last* is false.  Raises :exc:`KeyError` if the *key* does
-        not exist::
+        not exist:
+
+        .. doctest::
 
             >>> d = OrderedDict.fromkeys('abcde')
             >>> d.move_to_end('b')
-            >>> ''.join(d.keys())
+            >>> ''.join(d)
             'acdeb'
             >>> d.move_to_end('b', last=False)
-            >>> ''.join(d.keys())
+            >>> ''.join(d)
             'bacde'
 
         .. versionadded:: 3.2