--- /dev/null
+// Copyright 2012 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.
+
+package xerrors_test
+
+import (
+ "fmt"
+ "time"
+)
+
+// MyError is an error implementation that includes a time and message.
+type MyError struct {
+ When time.Time
+ What string
+}
+
+func (e MyError) Error() string {
+ return fmt.Sprintf("%v: %v", e.When, e.What)
+}
+
+func oops() error {
+ return MyError{
+ time.Date(1989, 3, 15, 22, 30, 0, 0, time.UTC),
+ "the file system has gone away",
+ }
+}
+
+func Example() {
+ if err := oops(); err != nil {
+ fmt.Println(err)
+ }
+ // Output: 1989-03-15 22:30:00 +0000 UTC: the file system has gone away
+}