diff --git a/doc/progs/eff_sequence.go b/doc/progs/eff_sequence.go
index 11c885a..c9b18ba 100644
--- a/doc/progs/eff_sequence.go
+++ b/doc/progs/eff_sequence.go
@@ -1,3 +1,5 @@
+// cmpout
+
 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.