The diagram looks complete. However, recall that we have not filled in the expression for the Is the list empty? stage. Right now, it's just an empty question. Without an expression, the robot will not be able to understand what an empty list means. What we will do in this section is to build the expression to indicate whether or not the list is empty.
The list will be considered empty when the Number of Items to Purchase is equal to 0. As long as there is at least one item in the list, we will need to purchase it. Alright, let's get to it.
- Double-click on the Is the list empty? stage to open up the properties dialog. Take a look at the bottom half of the dialog, as shown in the following screenshot.
The Expression ...
