code: func (a *author) add(src *author) {
  	if src == nil {
  		return
  	}
  	a.Emails = append(a.Emails, src.Emails...)
  	a.Names = append(a.Names, src.Names...)
  	a.Commits += src.Commits
  	if src.Role != "" {
  		a.Role = src.Role
  	}
  	if src.URL != "" {
  		a.URL = src.URL
  	}
  }
docs: // add merges src's fields into a's.