class IDGenerator:
    def __init__(self, max_id: int):
        self._i = 0
        self._mi = max_id

    def get(self):
        try:
            return self._i
        finally:
            self._i += 1
            if self._i > self._mi:
                self._i = 0

id_gen = IDGenerator(10)
print(id_gen.get())

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 11, in get
AttributeError: 'int' object has no attribute '_i'