class Foo:
def invalid_append(self):
paths: list[str] = []
paths.append(self)
class Bar:
foos: list[Foo]
def __init__(self, foos: list[Foo]) -> None:
self.foos = foos
def add_foo(self, foo: Foo):
self.foos.append(foo)
def invalid_add_foo(self):
self.foos.append(1)
_ = Bar([Bar([])])