private function _trace($trace = null)
    {
        $trace = $trace ?: debug_backtrace();
        foreach( $trace as $er) {
            $func = isset($er['function'])? $er['function']: '';
            $file = isset($er['file']) ? $er['file'] : '';

            # last two sections of the path
            if ($file) {
                $file  = $this->limitPath($file);
                $line  = isset($er['line'])? $er['line']: '';
                $class = isset($er['class'])? $er['class']: '';
                if ($class == 'IrfanTOOR\Debug' && $func=='_trace')
                    continue;

                $ftag = ($class != '') ? $class . '=>' . $func . '()' : $func . '()';
                $txt = '-- file: ' . $file . ', line: ' . $line . ', ' . $ftag;
                if ($this->terminal)
                    $this->console->writeln( $txt, 'dark');
                else
                    echo '<code style="color:#999">' . $txt . '</code><br>';
            }
        }
    }