CLN: Import pyplot as the function level.
WIP: messy
WIP: jit works but not much faster
WIP Good in Python but not in numba. Loop moved inside.
WIP: _refine compares and locate returns results. Nosetests error.
WIP: Comment out memo decorators. Smoke test runs without error.
WIP: Mute llvm DEBUG logging.
WIP: Reinstate memoization.
WIP: Wrap _refine in Python-friendly refine.
WIP: Whole pixel test fails but does not error.
WIP: Updating slice does not break code but whole pixel tests is still wrong.