--- a/errors.go	Sun Oct 16 11:52:01 2016 +0200
+++ b/errors.go	Sun Oct 16 12:20:29 2016 +0200
@@ -1,3 +1,7 @@
+// Copyright (C) 2016 Mikael Berthe <mikael@lilotux.net>. All rights reserved.
+// Use of this source code is governed by the MIT license,
+// which can be found in the LICENSE file.
+
 package takuzu
 
 import "fmt"