code: func NewLocalizer(bundle *Bundle, langs ...string) *Localizer {
  	return &Localizer{
  		bundle: bundle,
  		tags:   parseTags(langs),
  	}
  }
docs: // NewLocalizer returns a new Localizer that looks up messages
  // in the bundle according to the language preferences in langs.
  // It can parse Accept-Language headers as defined in http://www.ietf.org/rfc/rfc2616.txt.