idea: maybe heuristic based function/method signature

it's a bit common in old libraries.

like in flask

```py
def create_environ(*args: t.Any, **kwargs: t.Any) -> WSGIEnvironment:
```

this tells nothing, but

```py
builder = EnvironBuilder(*args, **kwargs)

try:
return builder.get_environ()
finally:
builder.close()
```

The body shows all the signatures.

Start by examining how Pyrefly currently represents and reports Python function and method signatures, then compare that behavior with the Flask examples in the issue. Define the heuristic and its expected output before identifying the relevant implementation and tests; done means signatures expose useful information from the function body without relying only on *args and **kwargs.

Written by the indexing model from the issue text.