Whitespace normalization.
diff --git a/Lib/difflib.py b/Lib/difflib.py
index 8493503..a2689f4 100644
--- a/Lib/difflib.py
+++ b/Lib/difflib.py
@@ -946,7 +946,7 @@
 
         yield "- " + aline
         if atags:
-             yield "? %s%s\n" % ("\t" * common, atags)
+            yield "? %s%s\n" % ("\t" * common, atags)
 
         yield "+ " + bline
         if btags: