[jsjohnst]

But the type signature of:

int -> int

Is wrong. At minimum it’s:

Optional[int] -> int

Because you provided a default value so clearly it’s not required to provide an input parameter. It’s also wrong to assume `0` is an int. There’s other valid types it could be. If the default was say `42`, I’d be pushing back a little less (outside of the Optional part), but this contrived example from GP had 0, which is ambiguous on what the inferred typing must be.