public function setField($fieldName = '', $fieldValue = '')
    {
        if (in_array($fieldName, array_keys($this->validFields))) {
            $this->fieldData[$fieldName] = $this->cleanString($fieldValue);
            if ($fieldName == 'LU_ENABLE_TOKEN') {
                if ($fieldValue) {
                    $this->fieldData['LU_TOKEN_TYPE'] = 'PAY_BY_CLICK';
                }
            }
            return true;
        }
        $this->debugMessage[] = 'SET FIELD: Invalid field in setField: ' . $fieldName;
        return false;
    }