code: func InjectFakeLogdogClient(c context.Context, client logdog.LogsClient) context.Context {
  	if client == nil {
  		panic("injecting nil logs client")
  	}
  	return context.WithValue(c, &fakeLogKey, client)
  }
docs: // InjectFakeLogdogClient adds the given logdog.LogsClient to the context.
  //
  // You can obtain a fake logs client from
  //   go.chromium.org/luci/logdog/api/endpoints/coordinator/logs/v1/fakelogs
  //
  // Injecting a nil logs client will panic.