:a = [1=2]

0 = {a == [5=2]}

0 = {a == [1=3]}

1 = {a == [1=2]}

:b = [1,2,3]

0 = {b == a}

0 = {b == []}

0 = {b == [3,1,2]}

0 = {b == [1,2,3,4]}

1 = {b == [1,2,3]}