[parhamn]

Whats the expected error in the example you gave? That x can't be none because it was received as a str?

[robertlagrant]

Yes, exactly. x would have to be str | None to be reachable.

[pawelkobojek]

Exactly - something along the lines of "Statement is unreachable".

[wiz21c]

isn't it perfectly valid to pass None to that function ? It's not like python enforces types at runtime nor at compile time. Right ?

[yesb]

Sure, it's valid python to do that. By that logic you could also pass an int. But the context of this post is that you're using a static type checker.

[Austizzle]

It's not valid from a typing perspective, but python will let you. If you want to disregard types though then none of this matters anyway and you won't get much benefit from these tools

[boxed]

Or that x is unused?