Sudoku.Board.GetValueOptions C# (CSharp) Method

        public IEnumerable<Values> GetValueOptions(Columns column, Rows row)
        {
            var usedValues = GetDeniedValues(column, row);

            for (int i = 0; i < 9; i++)
            {
                Values candidate = (Values)(1 << i);
                if ((usedValues & candidate) == Values.None)
                    yield return candidate;
            }
        }