coming from https://velog.io/@whitehousechef/%EB%B0%B1%EC%A4%80-1541%EB%B2%88-%EC%9E%83%EC%96%B4%EB%B2%84%EB%A6%B0-%EA%B4%84%ED%98%B8
ifinstance is a boolean function to check if something is of a type that we are looking for.
