I found this one extremely frustrating. The example implies that you should be able to use “setGear()” without passing a variable in the parentheses, but of course you do need to, and then you need to assign it to this.gear.
There has been no previous discussion of the keyword ‘this’; that’s one thing that makes this lesson difficult to complete. I spent some time with https://www.w3schools.com/js/js_this.asp in order to complete this lesson.