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This PR fixes the issues detailed in #11913. One of the main strategies for accommodating the fact that an empty list inherently changes the result of the return-type, is having the first overloads be that of
Iterable[Never]
, which will match an empty iterable first. Since the typing was fairly inaccurate before, I'm presuming a lot of repos will have new typing errors as a result of this change.Let's walk through some examples (all with Pyright) of the new behavior:
Empty list will always evaluate to 1
Given an empty list, but a start, the result will always be the type of the start:
Another example, where the list is filled out:
With multiple types: