gistfile1.txt

    /**
     * Build Validator Method.
     *
     * @param Validator $validator
     *
     * @return Validator $validator
     */
    protected function _buildValidator(Validator $validator)
    {
        return $validator
            ->notBlank('first_name', __('Your first name is required.'))
            ->notBlank('last_name', __('Your last name is required.'))
            ->creditCard('card_number', [
                'amex',
                'visa',
                'disc',
                'mc',
            ], __('Please enter a valid credit card number.'))
            ->notBlank('card_number', __('Credit Card number is required.'))
            ->notBlank('amount', __('Please enter an amount.'));
    }