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Always follow 3-2-1 backup rule
(sh.itjust.works)
Post funny things about programming here! (Or just rant about your favourite programming language.)
Like most things in life, context matters. In the OP it seems like the
checkfunction is used specifically so it could raise aPaymentExceptionif the payment hasn't been received... That's not a "forgiveness/permission" context, this is a yes or no question, hence should have been an if.