1..12
ok 1 - (0, 0) => undef                # Growing up in Sweden
ok 2 - (0, 1) => undef
ok 3 - (1, 0) => undef
ok 4 - (1, 1) => AB                   # The early years
ok 5 - (2, 1) => ABA                  # still experimental
ok 6 - (3, 1) => ABAA
ok 7 - (4, 1) => ABAAA                # Eurovision
ok 8 - (1, 2) => ABB                  # Waterloo, Mama Mia 
ok 9 - (2, 2) => ABBA                 # Dancing Queen
ok 10 - (7, 6) => ABABABABABABA    
ok 11 - (3, 3) => ABBABA              # All falls apart 
ok 12 - (4, 14) => ABBBBBABBBBBABBBBA # Tribute bands abound