code: func (p *Process) IsValid() error {
  	// Ensure that processes marked as NoService can't be scaled up.
  	if p.NoService {
  		if p.Quantity != 0 {
  			return errors.New("non-service processes cannot be scaled up")
  		}
  	}
  
  	return nil
  }
docs: // IsValid returns nil if the Process is valid.