Lesson 22 Practice 1 uses the walrus operator without it being introduced

[brgillis]

Issue description:
The initial code for this practice is:

var waiting_orders := []
var completed_orders := []

func complete_current_order():

Which uses the walrus operator (:=) to initialize arrays rather than the simple = for assignment that's been used so far. This operator isn't introduced properly until Lesson 27, so its use here is likely confusing (I had to go and look up what it does in GDScript when I noticed it and couldn't figure out on my own why it was used here).