memoization

[F1LM1]

Working on memoizing timecorr—need to have hashable parameters (then we can simply use Python's @lru_cache).

I've written a function that converts np.array and lists of np.array (non-hashable) into tuples (hashable when data is static) and back, but still can't think of a good way to hash any functions that may be passed in as parameters.