Page 122, Item 46, line 9 from bottom

[dspinellis]

p = s.client(q, r).booking(x).period(y, checkout(z)).duration();

should be read as

d = s.client(q, r).booking(x).period(y, checkout(z)).duration();

This makes the assignment consistent with the refactored code that follows it.

Thanks to: Toshiaki Kurokawa