2-to-3 fixup for map() example in docs

Doc/library/operator.rst

@@ -387,7 +387,7 @@ expect a function argument.
 
       >>> inventory = [('apple', 3), ('banana', 2), ('pear', 5), ('orange', 1)]
       >>> getcount = itemgetter(1)
-      >>> map(getcount, inventory)
+      >>> list(map(getcount, inventory))
       [3, 2, 5, 1]
       >>> sorted(inventory, key=getcount)
       [('orange', 1), ('banana', 2), ('apple', 3), ('pear', 5)]