public CrawlerIdle()
 {
     if (_instance != null)
     {
         return;
     }
     _instance        = this;
     _attackReference = CrawlerAttack.Instance;
 }
 public CrawlerAttack()
 {
     if (_instance != null)
     {
         return;
     }
     _instance         = this;
     _idleReference    = CrawlerIdle.Instance;
     _retreatReference = CrawlerRetreat.Instance;
 }