public IEnumerable <Util.Tuple <Cell, CellValue> > GetFilledCells(Cell cellA, Cell cellB)
    {
        Int3 cellIntA = cellA.ToInt3();
        Int3 cellIntB = cellB.ToInt3();

        Int3 min = Int3.Min(cellIntA, cellIntB);
        Int3 max = Int3.Max(cellIntA, cellIntB) + Int3.one();

        // Int3 mins3 = mins.ToInt3();
        // Int3 maxs = inclusiveMaxs.ToInt3() + Int3.one();
        foreach (Int3 u in Int3.Enumerate(min, max))
        {
            CellValue val = GetCellValue(new Cell(u));
            if (val.blockType != BlockShape.Empty)
            {
                yield return(new Util.Tuple <Cell, CellValue>(new Cell(u), val));
            }
        }
    }