public function playAudio(/* polymorphic */)
  {
    $args = Ensure::Input(func_get_args());
    $url = new URIResource($this->getAudioUrl());
    $data = $args->get(); 

    /** update add simplicity. playAudio('audioFile') = playAudio(array('audioFile' => 'audioFile')) **/
    if ($args->is_string()) {
      $data = array(
        "fileUrl" => $data
      );
    }

    $this->client->post((string) $url, $data);
  }