private void CheckGhost()
    {
        Ghost ghost = null;

        if (!pet.upstairFirst)
        {
            if (pet.checkDownstair)
            {
                ghost = PetUtility.GetDownstairGhost(pet.transform.position);
            }
            if (pet.checkUpstair && (ghost == null))
            {
                ghost = PetUtility.GetUpstairGhost(pet.transform.position);
                //Debug.Log("check downstair");
            }
        }
        else
        {
            if (pet.checkUpstair)
            {
                ghost = PetUtility.GetUpstairGhost(pet.transform.position);
            }
            if (pet.checkDownstair && (ghost == null))
            {
                ghost = PetUtility.GetDownstairGhost(pet.transform.position);
                //Debug.Log("check downstair");
            }
        }
        if (ghost != null)
        {
            //Debug.Log("we found ghost: " + ghost.name);
            pet.enemyInHouse = true;
            pet.enemy        = ghost.gameObject;
        }
        else
        {
            pet.enemyInHouse = false;
            pet.enemy        = null;
        }
    }