diff --git a/Lib/xml/sax/saxutils.py b/Lib/xml/sax/saxutils.py
index 1abcd9a..1b89e31 100644
--- a/Lib/xml/sax/saxutils.py
+++ b/Lib/xml/sax/saxutils.py
@@ -98,14 +98,17 @@
         except AttributeError:
             pass
     # wrap a binary writer with TextIOWrapper
-    class UnbufferedTextIOWrapper(io.TextIOWrapper):
-        def write(self, s):
-            super(UnbufferedTextIOWrapper, self).write(s)
-            self.flush()
-    return UnbufferedTextIOWrapper(buffer, encoding=encoding,
+    return _UnbufferedTextIOWrapper(buffer, encoding=encoding,
                                    errors='xmlcharrefreplace',
                                    newline='\n')
 
+
+class _UnbufferedTextIOWrapper(io.TextIOWrapper):
+    def write(self, s):
+        super(_UnbufferedTextIOWrapper, self).write(s)
+        self.flush()
+
+
 class XMLGenerator(handler.ContentHandler):
 
     def __init__(self, out=None, encoding="iso-8859-1"):