Unexpected behavior when arg is input as a string or literally same integer

[shenrun]

@ring.dict({})
def f(a):
    print("not using cache")
    return str(a)
f(1)
f.storage.backend
f("1")
f.storage.backend

The output is shown as below: not using cache '1' {'main.f:1': '1'} '1' {'main.f:1': '1'}