* Done: Product: Make list of lists cartesian product

* Done: Combine (c): transponse

* Done: All-pair (a): Go from [x, [a, b, c, ...]] to [[x, a], [x, b], ...]

* Done: Something (l): convert to binary.

* Done: Inverse l: from binary

* Done: Inverse sum: wrap in list.

* Done: Inverse product of int: is_prime

* Done: Update index(es) (u)

* Done: Constant (k): always 0

* Done: Reverse-lookup (v): Search over all ints + uniform lists for one that produces the desired output

* Done: Deep index: (j): Given list and func, apply func to list length, then deep-index the result into the list.

* Done: Deduplicate (d).

* Int ops:

    * Done: Permutations (c).

    * Done: All lists of all lengths up to the input. Permuted subsets (e).

    * Done: All partitions (of indices) (d).