Try Ruby is a interactive shell that quickly and whimsically teaches the Ruby programming language. Originally _why's idea, it has been recreated from the ground up by Rubyists who have a passion for Ruby and for teaching their fellow (wo)man how to program.
Running through the tutorial, it hits a snag at the following step:
blog.each do |entry|
.. h2 entry.title
.. p entry.fulltext
.. end
NoMethodError: undefined method `h2' for main:Object