docs: function Strategy(options, verify) {
    options = options || {};
    options.authorizationURL = options.authorizationURL || 'https://auth.login.yahoo.co.jp/yconnect/v1/authorization';
    options.tokenURL = options.tokenURL || 'https://auth.login.yahoo.co.jp/yconnect/v1/token';
    options.scopeSeparator = options.scopeSeparator || ' ';
  
    OAuth2Strategy.call(this, options, verify);
    this.name = 'yj';
    this._profileURL = options.profileURL || 'https://userinfo.yahooapis.jp/yconnect/v1/attribute';
    this._profileFields = options.profileFields || null;
  }