public function appendExceptionSuffix($message = null, $filename = null, $lineNumber = null)
    {

        // query whether or not a filename has been passed
        if ($filename === null) {
            $filename = $this->getFilename();
        }

        // query whether or not a line number has been passed
        if ($lineNumber === null) {
            $lineNumber = $this->getLineNumber();
        }

        // if no message has been passed, only return the suffix
        if ($message === null) {
            return sprintf(' in file %s on line %d', $filename, $lineNumber);
        }

        // concatenate the message with the suffix and return it
        return sprintf('%s in file %s on line %d', $message, $filename, $lineNumber);
    }