What is the ruling if a husband says, 'If you have one period, you are divorced, then if you have two periods, you are divorced'?

Primary text

If the husband says, 'If you have one period, you are divorced, then if you have two periods, you are divorced,' the second pronouncement does not take effect until she purifies from the third period. This is because the conjunction 'then' (thumma) implies sequence, requiring two full periods to occur subsequent to the first pronouncement of divorce.