public static function camelCase($str, $firstChar = 'lcfirst')
    {
        $str = str_replace(['-', '_', '.'], ' ', $str);
        $str = mb_convert_case($str, MB_CASE_TITLE);
        $str = str_replace(' ', '', $str); //ucwords('ghjkiol|ghjklo', "|");
        
        if (!function_exists($firstChar)) {
            $firstChar = 'lcfirst';
        }
        $str = call_user_func($firstChar, $str);
        
        return $str;
    }