Conditonally define module after initialization to None

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
20/100
Issue type
Feature
Clarity
Needs clarification
Activity status
Stale
Tech stack
python
Domain
compilers

Research direction

Start by reading the discussion in #649 and the conditional-import example in this issue. The issue's completion criterion is support for module types that begin as partial None types and switch to the imported module type.

Written by the indexing model from the issue text.

Description

false-positive feature priority-1-normal

Mypy complains about this code, even though it's valid Python:

if x:
    m = None
else:
    import m

The most obvious way to fix this would be to add support for "module types" for specific modules. In the above example, m would be a variable with a partial None type initially. The import statement would switch the partial type to the type of module m.

(This is derived from discussion in #649.)

Dominant language
Python
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