Just to follow up, it looks like everyone on the mailing list prefers the API where the `*_like` functions return a new array with the mask set to `nomask`, rather than copying the input array's mask, and that's my intuition as well. Want to update the PR to do that? (Or if you have an argument for why it should be the other way around, bring that up on the list?)

Also Pierre GM made a suggestion for how the `_convert2ma` function might be changed that you might want to take a look at.