i go to the library customer service to collect a book i'd requested, and they ask if i would like to renew my premium membership for next year. being short i say not today and they say well then you wouldn't be able to collect your book. why not? because you've got five already, yes, but i get eight, no you don't, because your membership is expiring, aha yes but it doesn't expire till the 24th of this month, and today is only the 8th, no, but your membership expires in 17 days, but the loan period is 21 days, so you need to renew it now to cover the last four days, well then couldn't you just make the due date the 24th, the day of the expiry, no we cannot, because the loan period is three weeks.

the devious beasts!