title: Is there a tutorial that teaches common Ruby programming idioms used by experienced programmers, but may not be obvious to newcomers?
body: <p>I'm looking for a Ruby's equivalent of <a href="http://python.net/~goodger/projects/pycon/2007/idiomatic/handout.html" rel="nofollow noreferrer">Code Like a Pythonista: Idiomatic Python</a></p>
  
  <p>Desirable features:</p>
  
  <ul>
  <li>easy to read</li>
  <li>single document which covers all topics: tips, tricks, guidelines, caveats, and pitfalls</li>
  <li>size less than a book</li>
  <li>idioms should work out of the box for the standard distribution (<code>% sudo apt-get install ruby irb rdoc</code>)</li>
  </ul>
  
  <p>Please, put one tutorial per answer if possible, with an example code from the tutorial and its meaning.</p>
  
  <p>UPDATE:</p>
  
  <p>These are the most closest to the above description resources I've encountered:</p>
  
  <ul>
  <li><a href="http://blog.angelbob.com/posts/244" rel="nofollow noreferrer">Ruby Idioms</a></li>
  <li><a href="http://www.rubyist.net/~slagell/ruby/index.html" rel="nofollow noreferrer">Ruby User's Guide</a></li>
  </ul>