Revisiting attribute docstrings

Placing the comma after the docstring introduces a syntax ambiguity:

def foo(
    param: str = "some default value"
    """Some documentation""",

Is that a string concatenation? Or is the second one a docstring? With today’s syntax, it’s a string concatenation, so if it’s now a docstring then that’s a backwards-incompatible syntax change.

On the other hand, I would agree with @BrenBarn that separating the parameter from its docstring with a comma would be egregious.