code: public function stats(?int $date = null): array
      {
          $date = $date ?: time();
  
          return json_decode($this->client->stats($this->name, $date), true);
      }
docs: Return the current statistics for a given queue on a given date.
  
  The results are returned are a JSON blob:
  <code>
  {
  # These are unimplemented as of yet
  'failed': 3,
  'retries': 5,
  'failures': 5,
  'wait': {
  'total'    : ...,
  'mean'     : ...,
  'variance' : ...,
  'histogram': [
  ...
  ]
  },
  'run': {
  'total'    : ...,
  'mean'     : ...,
  'variance' : ...,
  'histogram': [
  ...
  ]
  },
  }
  </code>
  
  @param  int $date The date for which stats to retrieve as a unix timestamp.
  @return array
  
  @throws QlessException