CubeIndex.ToString C# (CSharp) Method

    public override string ToString()
    {
        return string.Format("[" + x + "," + y + "," + z + "]");
    }

    public List <Tile> TilesInRange(Tile center, int range)
    {
        //Return tiles rnage steps from center, http://www.redblobgames.com/grids/hexagons/#range
        List <Tile> ret = new List <Tile>();
        CubeIndex   o;

        for (int dx = -range; dx <= range; dx++)
        {
            for (int dy = Mathf.Max(-range, -dx - range); dy <= Mathf.Min(range, -dx + range); dy++)
            {
                o = new CubeIndex(dx, dy, -dx - dy) + center.index;
                if (grid.ContainsKey(o.ToString()))
                {
                    ret.Add(grid[o.ToString()]);
                }
            }
        }
        return(ret);
    }