.. versionadded:: 1.2
+``JSON_PRESERVE_ORDER``
+ If this flag is used, object keys in the output are sorted into the
+ same order in which they were first inserted to the object. For
+ example, decoding a JSON text and then encoding with this flag
+ preserves the order of object keys.
+
+ .. versionadded:: 1.3
+
The following functions perform the actual JSON encoding. The result
is in UTF-8.