text: function signupVerification(user, context, callback) {
    var CLIENTS_WITH_VERIFIED_SIGNUP = ['YOUR CLIENT ID', ...];
    if (CLIENTS_WITH_VERIFIED_SIGNUP.indexOf(context.clientID) !== -1) {
      user.app_metadata = user.app_metadata || {};
      if (user.app_metadata.verified === false) {
        var msg = 'Signup email verification must be completed before signin';
        console.error(msg);
        return callback(new UnauthorizedError(msg));
      }
    }
    callback(null, user, context);
  }
  