iscoroutinefunction should use TypeIs

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Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
64/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Quiet
Tech stack
python
Domain
tooling

Research direction

Locate the typeshed stub entry for inspect.iscoroutinefunction and compare its annotation with the other inspect is... functions that use TypeIs. Update the annotation so both branches narrow as described, then run the relevant type-checking tests to confirm coroutine functions and the else branch are narrowed correctly.

Written by the indexing model from the issue text.

Description

stubs: improvement

One of the things I find myself writing a lot is

if iscoroutinefunction(myfunction):
    do_something_with_async(myfunction)
else:
    do_something_with_just_sync(myfunction)

however the else block doesn't narrow the type to non-awaitable. Shouldn't it? Some of the other is... functions in inspect seem to use TypeIs as well.

Dominant language
Python
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Avg merge
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Merged PRs (30d)
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