code: public function get($userId, $callId)
      {
          $key = $this->getCacheKey($userId, $callId);
          if (!isset($this->cache[$key])) {
              $data = $this->getStorage()->get($userId, $callId);
              $state = is_null($data) ? self::STATE_NOT_FOUND : self::STATE_ALIGNED;
              $this->putInCache($key, $userId, $callId, $data, $state);
          }
  
          return $this->getFromCache($key);
      }
docs: Gets a dataset from the store using the provided keys.
  Will return null if the dataset doesn't exist.
  
  @param string $userId
  @param string $callId
  @return string