code: func getOwnServiceIdentity(c context.Context, signer signing.Signer) (identity.Identity, error) {
  	if signer == nil {
  		return "", ErrNotConfigured
  	}
  	serviceInfo, err := signer.ServiceInfo(c)
  	if err != nil {
  		return "", err
  	}
  	return identity.MakeIdentity("service:" + serviceInfo.AppID)
  }
docs: // getOwnServiceIdentity returns 'service:<appID>' identity of the current
  // service.