$ python3 ./queens.py ['a1', 'b7', 'c5', 'd8', 'e2', 'f4', 'g6', 'h3'] ['a1', 'b7', 'c4', 'd6', 'e8', 'f2', 'g5', 'h3'] ['a6', 'b1', 'c5', 'd2', 'e8', 'f3', 'g7', 'h4'] ['a4', 'b1', 'c5', 'd8', 'e2', 'f7', 'g3', 'h6'] ['a5', 'b1', 'c8', 'd4', 'e2', 'f7', 'g3', 'h6'] ['a3', 'b1', 'c7', 'd5', 'e8', 'f2', 'g4', 'h6'] ['a5', 'b1', 'c4', 'd6', 'e8', 'f2', 'g7', 'h3'] ['a7', 'b1', 'c3', 'd8', 'e6', 'f4', 'g2', 'h5'] ['a5', 'b1', 'c8', 'd6', 'e3', 'f7', 'g2', 'h4'] ['a5', 'b3', 'c1', 'd7', 'e2', 'f8', 'g6', 'h4'] ['a5', 'b7', 'c1', 'd4', 'e2', 'f8', 'g6', 'h3'] ['a6', 'b3', 'c1', 'd8', 'e4', 'f2', 'g7', 'h5']