'Returns whether correctness is available now, for the given attributes.'

@classmethod
def correctness_available(cls, show_correctness='', due_date=None, has_staff_access=False):

    if (show_correctness == cls.NEVER):
        return False
    elif has_staff_access:
        return True
    elif (show_correctness == cls.PAST_DUE):
        return ((due_date is None) or (due_date < datetime.now(UTC)))
    return True
