Exercise 17.4.4 --> 4 actually works

[niloofar-dehdari-ebrahimi]

I am not an expert. But the question number 4 asks:

Why can’t (today() %--% (today() + years(1))) / months(1) work?

However, when I run it in the console, it returns: 12

[davidrsch]

This exercise came from previous version of the book, that most likely was build using lubridate 1.6.0 or a previous version, where doing this operation returned an error message. Maybe they can take it out next time they review it, @mine-cetinkaya-rundel ?