Function lean_py_to_string

LeanPy/native/python_bridge.c:600–603

    if (!s) return raise_py_error();
    const char *cs = p_PyUnicode_AsUTF8(s);
    if (!cs) {
        p_Py_DecRef(s);
        return raise_py_error();
    }
    lean_object *out = lean_mk_string(cs);
    p_Py_DecRef(s);
    return lean_io_result_mk_ok(out);