code: function() {
          var sId;
  
          // Do this cleanup only if there are sessions
          if (Object.keys(_sessions).length > 0) {
              _log.info("_cleanupWindowlessSessions", "Asynchronous Sessions clean-up phase starting NOW");
              for (sId in _sessions) {
                  if (_sessions[sId].getWindowsCount() === 0) {
                      _deleteSession(sId);
                      _log.info("_cleanupWindowlessSessions", "Deleted Session '"+sId+"', because windowless");
                  }
              }
          }
      }
docs: private: