code: function canNotify(value) {
    if (!value) {
      var why = value === false ? 'blocked' : 'unacknowledged';
      var reason = 'not permitted by user (' + why + ')';
      return Promise.reject(new Error(reason));
    }
    return Promise.resolve();
  }
docs: @summary
  Determines if notification should proceed.
  
  @description
  Notification shall <strong>not</strong> proceed unless `value` is true.
  
  `value` will equal one of:
  <ul>
  <li><code>true</code> (from `isPermitted`)</li>
  <li><code>false</code> (from `isPermitted`)</li>
  <li><code>undefined</code> (from `Promise.race`)</li>
  </ul>
  
  @private
  @param {boolean|undefined} value - Determines if notification permissible.
  @returns {Promise<undefined>} Notification can proceed