Add version note about set literals.

diff --git a/Doc/library/stdtypes.rst b/Doc/library/stdtypes.rst
index 8dc36bc9009f4c9f7728a0b215f23df9355bd310..5c47e9bb58e30a96f2133274738a3bddaea0525a 100644 (file)
--- a/Doc/library/stdtypes.rst
+++ b/Doc/library/stdtypes.rst
@@ -1672,13 +1672,13 @@ There are currently two built-in set types, :class:`set` and :class:`frozenset`.
 The :class:`set` type is mutable --- the contents can be changed using methods
 like :meth:`add` and :meth:`remove`.  Since it is mutable, it has no hash value
 and cannot be used as either a dictionary key or as an element of another set.
-The :class:`frozenset` type is immutable and :term:`hashable` --- its contents cannot be
-altered after it is created; it can therefore be used as a dictionary key or as
-an element of another set.
+The :class:`frozenset` type is immutable and :term:`hashable` --- its contents
+cannot be altered after it is created; it can therefore be used as a dictionary
+key or as an element of another set.
 
-Non-empty sets (not frozensets) can be created by placing a comma-separated list
-of elements within braces, for example: ``{'jack', 'sjoerd'}``, in addition to the
-:class:`set` constructor.
+As of Python 2.7, non-empty sets (not frozensets) can be created by placing a
+comma-separated list of elements within braces, for example: ``{'jack',
+'sjoerd'}``, in addition to the :class:`set` constructor.
 
 The constructors for both classes work the same: