code: func (o *CreateTagOptions) Validate(r *Repository, hash plumbing.Hash) error {
  	if o.Tagger == nil {
  		return ErrMissingTagger
  	}
  
  	if o.Message == "" {
  		return ErrMissingMessage
  	}
  
  	// Canonicalize the message into the expected message format.
  	o.Message = strings.TrimSpace(o.Message) + "\n"
  
  	return nil
  }
docs: // Validate validates the fields and sets the default values.