/// <summary> <!-- {{{1 --> Convert the index to String
/// </summary>
/// <param name="self"></param>
/// <returns></returns>
public static string ToStr(this SudokuCellIndex self)
{
return(self.ToInt().ToString());
}
/// <summary> <!-- {{{1 --> Get cell from cell index
/// </summary>
/// <param name="idx"></param>
/// <returns></returns>
public Cell CellFromIndex(SudokuCellIndex idx)
{
idx.AssertWhenInvalid();
return(this.board.ElementAt(idx.ToInt()));
}