Handling @overload with a docstring declaration

[arnav-jain1]

fixes #359. Added a check to make sure the body was not a docstring. Also added a test in the the third_party folder to show that the change is working. Let me know if anything needs to be changed.

[yangdanny97]

Thanks!

The third_party/conformance tests are pulled from the typing spec conformance test suite, and shouldn't be modified directly here: https://github.com/python/typing/tree/main/conformance

For this type of feature, could you please add an integration test here? https://github.com/facebook/pyrefly/blob/main/pyrefly/lib/test/overload.rs

Also, I think we should only allow docstrings for function bodies if there is an @overload decorator

For example, a program like this should still be invalid:

def foo() -> int:
    """hello"""

[yangdanny97]

Back to you with comments, lmk if you have any questions. Thanks!

[arnav-jain1]

Should be fixed. Added 3 test cases, first one is the basic one. Second one was to make sure that stuff after a docstring would still be typechecked properly and if the body of the function had more info, it wouldn't deem it a stub. The last one is for the case you mentioned of the nonoverloaded function with a docstring.

[arnav-jain1]

My commits are a bit messy because I am a little new to this but the code should be right

[arnav-jain1]

Also if you have others that you want me to fix, let me know! I am a bit swamped right now but I can try and get to it soon.

[facebook-github-bot]

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