public List<Tile> GetWalkableNodes()
    {
        Debug.Log("this is " + this.transform.name);
        List<Tile> walkable = new List<Tile>();
        foreach (KeyValuePair<Direction, Tile> hashMap in connection)
        {
            if (hashMap.Value != null)
            {
                //if it is walkable and is not occupied
                if (hashMap.Value.isWalkable)
                {
                    Debug.Log("walkable node :"+hashMap.Value.transform.name);
                    Debug.Log("direction: "+hashMap.Key.ToString());
                    walkable.Add(hashMap.Value);
                }
            }
        }
        Debug.Log(walkable.Count);
        return walkable;
    }