t(key) {
    const lang = this._language()
    const fallbackLang = this._messages['en']
    const i18n = lang && this._messages[lang] || fallbackLang
    return i18n[key] || fallbackLang[key] || key
  }
Gets a translated string for the given key.
@method t
@param {String} key the key to all messages
@return {String} translated label