Apparently this is code from Martin Rinehart’s “Edges to Rubies” series.
It is quite old and doesn’t use operations.
It also lacks the commentary that you’d expect in a tutorial script.
It has annoying outdented comments, and strange indentation. (As I recall he was a proponent of forcing everyone at SCF and those writing code for SketchUp, to use the same indentation in all languages. Ie, Python, Java, JavaScript, HTML, XML, Ruby, etc. There was a big long argument topic at SCF over this. So he basically choose his own indentation, rejecting the Ruby norm, and posted his tutorials at his own website.)
If there are going to be these kinds of basic errors in his tutorials, it is tempting me to remove the link to them from the Ruby Learning Resources wikilist.