1) Consider JOURNAL Array in chap4.js
* Add code to show that each Entry has exactly
one of these: 'work' and 'weekend'
* Make a Map w that keeps number of each activity
on weekends. w.get('pizza') is the number of
Entry's that include 'weekend' and 'pizza'
2. Copy your inch-cm converter to another file and use
a converter class similar to Temperature in chap6.js