On page 52 and 53 you use Array.prototype.slice.call(null, arguments) in all of the methods.
For me this results in “TypeError: Array.prototype.slice called on null or undefined” no on node.js 0.10.x with or w/o –harmony passed in.
Array.prototype.slice.call(arguments) seems to work for me, but I was curious if I’m misunderstanding something or doing something wrong that is causing me to see this error. I’m still somewhat new to JS, and therefore wanted to confirm.
Outside of this, the book has been amazing so far.