http://rafekettler.com/talks/sinatra.html
A tech talk originally given at the Dining Philosopher's Newbie Hackathon at the University of Pennsylvania on December 9, 2012.
Assuming you already have a suitable ruby and rubygems installation (if not, go to http://rvm.io), just run gem install bundler (again, if you haven't already), then run bundle install. You should be able to run all of the code snippets.
To run the server for a particular stage, simply type ruby stageX.rb. C-c or C-d when you're done to kill the script.
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