Can you add a comment explaining why this sequence is repeated?

Done. Also added a test case to make sure that clearing one function's overloads doesn't clear another.

Thinking out loud, clear_overloads() is becoming the most complicated part of this. Perhaps we don't need to support clearing overloads per function, which would simplify it greatly. Use cases I can think of are:

• You want to save some memory after importing all your code -> you call clear_overloads() and get rid of them all.
• You are constantly reloading a module with overloads in it and changing the line numbers. Then maybe you want to clear_overloads() for just that function. But that seems really exotic.

So maybe we should only support clearing the whole overload registry at once. Can you think of other realistic reasons people may want to use clear_overloads()?

Hm. Given the reload(module) use case, maybe the only options should be clear all or clear a specific module? The new data structure makes that easy. The question would then be whether the argument should be the (full) module name or the module object? (Or either?) The sequence of events would be something like

typing.clear_overload(mod)
importlib.reload(mod)

I can't really think of a use case for clearing a specific function. Did you have one in mind originally? Or was it just convenient for testing?

I think for now we should allow only clearing the whole registry. I see the use case for wanting to repeatedly reload modules while wanting to introspect overloads, but it seems unlikely to be common. We can always add an argument later to clear overloads by module if someone asks for it, but once we add it we're stuck with it.