cartesian
Returns the cartesian product between each list in this (i.e. every possible list formed by choosing an element from each of the sublists where order matters). Elements in each sub-list must have homogeneous elements.
e.g. this = [A, B, C, D, X, Y] => [A, C, X, A, C, Y, A, D, X, A, D, Y, B, C, X, B, C, Y, B, D, X, B, D, Y]