code: func (e *Instance) Proto() *api.Instance {
  	return &api.Instance{
  		Package:      e.Package.StringID(),
  		Instance:     common.InstanceIDToObjectRef(e.InstanceID),
  		RegisteredBy: e.RegisteredBy,
  		RegisteredTs: google.NewTimestamp(e.RegisteredTs),
  	}
  }
docs: // Proto returns cipd.Instance proto with information from this entity.