code: public function getDiscUsageAsync(Requests\GetDiscUsageRequest $request) 
      {
          return $this->getDiscUsageAsyncWithHttpInfo($request)
              ->then(
                  function ($response) {
                      return $response[0];
                  }
              );
      }
docs: /*
  Operation getDiscUsageAsync
  
  Check the disk usage of the current account
  
  @param Requests\GetDiscUsageRequest $request is a request object for operation
  
  @throws \InvalidArgumentException
  @return \GuzzleHttp\Promise\PromiseInterface