Instafilter\Image::check_extension PHP Метод

    protected function check_extension($filename, $writevar = true)
    {
        $return = false;
        foreach ($this->accepted_extensions as $ext) {
            if (strtolower(substr($filename, strlen($ext) * -1)) == strtolower($ext)) {
                $writevar and $this->image_extension = $ext;
                $return = $ext;
            }
        }
        return $return;
    }