[rue]

The article is actually about a revisit.

Lots of folks could spend similar time getting familiar with the core classes, be it just in irb/ripl (the REPL) using Object#methods, Class#instance_methods &c., using the command-line ri tool (e.g. $ ri Array) or one of the web-based doco sites: rubydoc.info, ruby-doc.org or apidock.com.

[zbrock]

If you really want to dig into objects in irb, you should check out https://github.com/matthew/method_lister

It'll give you a really good idea of where all those methods on your objects come from.

[halostatue]

My guess is it's the British usage, as in "revising for an exam."