Hi Serhiy,

    hi: Py_ssize_t(py_default="len(a)") = -1

Won't works, as pydoc will use the inspect module (_signature_fromstr) to get the signature. _signature_fromstr expects a valid python signature, but `def foo(a, x, lo=0, high=len(a)): pass` is not valid (SyntaxError).

Should we note that in the clinic documentation:

> py_default
>     default as it should appear in Python code, as a string. Or None if there is no default.

> py_default
>     default as it should appear in valid Python code, as a string. Or None if there is no default.

?