text: /**
   * @title Whitelist
   * @overview Only allow access to users with specific whitelist email addresses.
   * @gallery true
   * @category access control
   *
   * This rule will only allow access to users with specific email addresses.
   *
   */
  
  function userWhitelist(user, context, callback) {
  
    // Access should only be granted to verified users.
    if (!user.email || !user.email_verified) {
      return callback(new UnauthorizedError('Access denied.'));
    }
  
    const whitelist = [ 'user1@example.com', 'user2@example.com' ]; //authorized users
    const userHasAccess = whitelist.some(
      function (email) {
        return email === user.email;
      });
  
    if (!userHasAccess) {
      return callback(new UnauthorizedError('Access denied.'));
    }
  
    callback(null, user, context);
  }
  