public ChessBoardBuilder Rank(int rank, string pieces) { CheckValidPieces(pieces); CheckValidRank(rank); var file = 0; foreach (var piece in pieces) { if (ValidPieces.Contains(piece.ToString().ToUpper())) { _board[file++, rank - 1] = piece; } else { Throw.BoardBuilder($"Don't know how to map '{piece}' for board building purposes"); } } return(this); }