public void TakeDamage()   //int damage) {
 {
     if (!_shieldActive && _lives > 0)
     {
         _lives--;
         DamageEngine();
         _uiManager.UpdateLives(_lives);
         if (_lives < 1)
         {
             Instantiate(_explosionPrefab, transform.position, Quaternion.identity);
             Destroy(gameObject);
             _enemySpawner.StopSpawning();
         }
     }
     else
     {
         // disable shield
         _shieldActive = false;
         _shield.SetActive(false);
     }
 }