public function all($app = NULL) : Array
    {
        if( ! is_string($app) )
        {
            if( $app === NULL )
            {
                $MLFiles = $this->getMLFiles();
            }
            elseif( is_array($app) )
            {
                $MLFiles = $app;
            }
            else
            {
                return false;
            }

            $allMLFiles = [];

            if( ! empty($MLFiles) ) foreach( $MLFiles as $file )
            {
                $removeExtension = $this->removeExtension($file);
                $allMLFiles[$removeExtension] = $this->all($removeExtension);
            }

            return $allMLFiles;
        }
        else
        {
            if( is_file($createFile = $this->_langFile($app)) )
            {
                $read = file_get_contents($createFile);

                return json_decode($read, true);
            }   

            return [];
        }
    }