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## Summary
Resolves#12636
Consider docstrings which begin with the word "Returns" as having
satisfactorily documented they're returns. For example
```python
def f():
"""Returns 1."""
return 1
```
is valid.
## Test Plan
Added example to test fixture.
---------
Co-authored-by: Dhruv Manilawala <dhruvmanila@gmail.com>
