diff -r 0eb093e40813 -r f8f7ae0f4d98 mercurial/revset.py
--- a/mercurial/revset.py	Wed Jul 15 04:45:58 2015 +0900
+++ b/mercurial/revset.py	Sun Jul 05 11:06:58 2015 +0900
@@ -115,6 +115,7 @@
     return baseset(sorted(reachable))
 
 elements = {
+    # token-type: binding-strength, prefix, infix, suffix
     "(": (21, ("group", 1, ")"), ("func", 1, ")")),
     "##": (20, None, ("_concat", 20)),
     "~": (18, None, ("ancestor", 18)),