What "check expected" does

The first time I saw check expected, I thought "this is easy, just need to replace all the symbols with an example."

But soon I realized how important it was, it shows the outcome we are expecting, and gave us a clear direction when writing the actual program. What's more, the check expected code helps me understand what I'm doing and what I'm supposed to do. 

Using check expected in programming is like setting a goal for the future in real life. You will easily get lost if you don't do that.