code: func SchedulingDuration(b *pb.Build) (duration time.Duration, ok bool) {
  	create, createErr := ptypes.Timestamp(b.CreateTime)
  	start, startErr := ptypes.Timestamp(b.StartTime)
  	if createErr != nil || create.IsZero() || startErr != nil || start.IsZero() {
  		return 0, false
  	}
  
  	return start.Sub(create), true
  }
docs: // SchedulingDuration returns duration between build creation and start.