code: public function purge($urls)
      {
          $urlString = $urls;
          if (is_array($urls)) {
              $urlString = implode("\n", $urls);
          }
  
          $client = new Client([
              'timeout' => $this->config->timeout
          ]);
          $response = $client->request('POST', Config::ED_PURGE, [
              'headers' =>  Signature::getPurgeSignHeader($this->config, $urlString),
              'form_params' => ['purge' => $urlString]
          ]);
          $result = json_decode($response->getBody()->getContents(), true);
          return $result['invalid_domain_of_url'];
      }
docs: 刷新缓存
  
  @param array|string $urls 需要刷新的文件 url 列表
  
  @return array 刷新失败的 url 列表，若全部刷新成功则为空数组