protected function findImport($url)
    {
        foreach ((array) $this->importDir as $dir) {
            $full = $dir.(substr($dir, -1) != '/' ? '/' : '').$url;
            if ($this->fileExists($file = $full.'.less') || $this->fileExists($file = $full)) {
                return $file;
            }
        }

        return;
    }