SynthesizedChess

def make_board(num_rows, num_columns):
    board = []
    for i in range(num_rows):
        board.append([])
        for j in range(num_columns):
            board[i].append(' ')
    return board

def print_row(row, row_number):
    row_text = str(row_number)
    if row_number < 10:
        row_text += ' '
    row_text += '│ '
    for item in row:
        row_text += str(item) + ' │ '
    print(row_text)

def print_board(board):
    print('  ┌───' + '┬───' * (len(board[0]) - 1) + '┐')

    for i in range(len(board) - 1):
        print_row(board[i], len(board) - i)
        print('  ├───' + '┼───' * (len(board[i]) - 1) + '┤')
        
    print_row(board[-1], 1)
    print('  └───' + '┴───' * (len(board[-1]) - 1) + '┘')
    alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
    column_letters = ' '
    for i in range(len(board[-1])):
        column_letters += '   ' + alphabet[i]
    print(column_letters)

def get_legal_moves(board, position):
    legal_moves = []
    for row in range(len(board)):
        for sq in range(len(board[row])):
            # Every space that is exactly 1 row and 2 columns or 2 rows and 1
            # column away from the knight.
            if (abs(row - position[0]) + abs(sq - position[1]) == 3 
               and abs(row - position[0]) < 3 and abs(sq - position[1]) < 3 
               and -1 not in [row, sq] and len(board) not in [row, sq]):
                legal_moves.append([row, sq])
    return legal_moves


length = 21
board = make_board(length, length)
position = [length//2, length//2]
len_1 = get_legal_moves(board, position)
for sq in len_1:
    board[sq[0]][sq[1]] = '1'
print_board(board)