I think the new `as_integer_ratio` also needs discussion: it was agreed at some point in the past to add `as_integer_ratio` *methods* on all numeric built-in types, and there's a PR for that. Adding `as_integer_ratio` as a new function too seems like two ways to do it.

Please can we defer to 3.9? There just isn't time for the design discussions that are needed, and I'd personally rather see the first version of the `imath` module be somewhat complete, with `is_prime` and `primes` already.

I do realise that from the perspective of adding an `imath` module, the accumulation of integer-based functions in the `math` module is something of a wart that we're making worse in 3.8, but I don't think rushing in this change is the solution.

Radical suggestion: should we consider delaying the inclusions of `comb`, `perm` and `isqrt` in the math module so that we can do this properly for 3.9?