The missing line would be x+= num
This means that every time a number is selected from the range it is added to the value of x.
I believe it would be the anchor element.
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Correct me if I'm wrong.
<span>END POINT : Snaps to the closest endpoint or corner of a geometric object. MID POINT : Snaps to the midpoint of a geometric object. CENTER : Snaps to the center of an arc, circle, ellipse, or elliptical arc.</span>