<reponame>Zhou-Yicheng/SUSTech-CS307-Project2-Python
class BaseError(Exception):
    pass


class EntityNotFoundError(BaseError):
    pass


class IntegrityViolationError(BaseError):
    pass

class BaseError(Exception):
    pass


class EntityNotFoundError(BaseError):
    pass


class IntegrityViolationError(BaseError):
    pass