protected function deleteMatchingFiles($wildcard, $ignored = null)
    {
        if (is_array($files = $this->files->glob($wildcard)))
        {
            foreach ($files as $path)
            {
                if ( ! is_null($ignored))
                {
                    // Spin through each of the ignored assets and if the current file path ends
                    // with any of the ignored asset paths then we'll skip this asset as it
                    // needs to be kept.
                    foreach ((array) $ignored as $ignore)
                    {
                        if (ends_with($path, $ignore)) continue 2;
                    }
                }

                $this->files->delete($path);
            }
        }
        
    }