## Summary
Related to #15848, this PR adds the imports explicitly as we'll now flag
these symbols as undefined.
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
## Summary
This PR adds type narrowing in `and` and `or` expressions, for example:
```py
class A: ...
x: A | None = A() if bool_instance() else None
isinstance(x, A) or reveal_type(x) # revealed: None
```
## Test Plan
New mdtests 😍
