update the tutorial to use str.format
diff --git a/Doc/tutorial/stdlib2.rst b/Doc/tutorial/stdlib2.rst
index 459d765..ed4c876 100644
--- a/Doc/tutorial/stdlib2.rst
+++ b/Doc/tutorial/stdlib2.rst
@@ -116,7 +116,7 @@
    >>> for i, filename in enumerate(photofiles):
    ...     base, ext = os.path.splitext(filename)
    ...     newname = t.substitute(d=date, n=i, f=ext)
-   ...     print '%s --> %s' % (filename, newname)
+   ...     print '{0} --> {1}'.format(filename, newname)
 
    img_1074.jpg --> Ashley_0.jpg
    img_1076.jpg --> Ashley_1.jpg