Meh. I appreciate the effort that went into it, and it's written well enough. Just not sure how useful this is anymore. It also neglects using `bind` instead of

Meh. I appreciate the effort that went into it, and it's written well enough. Just not sure how useful this is anymore. It also neglects using `bind` instead of `call` or `apply`, which is often a better approach. I think the general consensus is moving away from callbacks and towards promises, especially since they're now in core JS.