public WorkerFlagReader(World world)
 {
     IsValid        = true;
     callbackSystem = world.GetExistingSystem <WorkerFlagCallbackSystem>();
     view           = world.GetExistingSystem <WorkerSystem>().View;
 }
 public WorkerFlagTracker(WorkerFlagCallbackSystem callbackSystem)
 {
     this.callbackSystem = callbackSystem;
     callbackKey         = callbackSystem.RegisterWorkerFlagChangeCallback(OnWorkerFlagChange);
 }