protected function copy($from, $to = null)
    {
        if (is_array($from) && is_null($to)) {
            foreach ($from as $key => $value) {
                $this->copy($key, $value);
            }

            return;
        }

        if (!file_exists($from)) {
            return;
        }

        $to = $this->extensionPath($to);

        $this->filesystem->copy($from, $to);
    }