def go_back(self):
        """Go back to a previous state if possible.

        It is impossible to go forward through the states without
        meeting certain requirements. Going backward is relatively
        easy with this method. Negative states are not allowed,
        and the verse-checking process may not be interrupted."""
        if self.__state != self.OPTIONS.CHECK:
            self.__state = max(0, self.__state - 1)
Go back to a previous state if possible.

        It is impossible to go forward through the states without
        meeting certain requirements. Going backward is relatively
        easy with this method. Negative states are not allowed,
        and the verse-checking process may not be interrupted.
recipes/Python/577046_Bible_Verse_Quiz__statepy/recipe-577046.py