Rename PyUnicode_AsString -> _PyUnicode_AsString and
PyUnicode_AsStringAndSize -> _PyUnicode_AsStringAndSize to mark
them for interpreter internal use only.

We'll have to rework these APIs or create new ones for the
purpose of accessing the UTF-8 representation of Unicode objects
for 3.1.
diff --git a/Misc/NEWS b/Misc/NEWS
index 3679a5b..1e22f70 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -15,6 +15,14 @@
 - Issue #1819: function calls with several named parameters are now on
   average 35% faster (as measured by pybench).
 
+- The undocumented C APIs PyUnicode_AsString() and
+  PyUnicode_AsStringAndSize() were made private to the interpreter, in
+  order to be able to refine their interfaces for Python 3.1.
+
+  If you need to access the UTF-8 representation of a Unicode object
+  as bytes string, please use PyUnicode_AsUTF8String() instead.
+
+
 Library
 -------