### Why is `Coroutine[Any, Any, T]` used instead of `Awaitable[T]`?
* Typing issues (PyCharm)
* Explicit expression of whether some sort of action is performed or not (futures vs coros)

### Why is `subset-verify-optimized` branch closed?
* Performance gain at large set sizes are 0% or less.
* Performance gain with caching is always negative.
* Using merge-based optimization is assumed to be even less practical.