code: func (mgr *MemorySessionManager) GarbageCollection() {
  	for k, v := range mgr.sessions {
  		if v.isExpired() {
  			delete(mgr.sessions, k)
  		}
  	}
  	time.AfterFunc(time.Duration(gcTimeInterval)*time.Second, mgr.GarbageCollection)
  }
docs: // GarbageCollection recycles expired sessions, delete them from the session manager.