title: Hidden features of Groovy?
body: <p>It seems like Groovy was forgotten in this thread so I'll just ask the same question for Groovy.</p>
  
  <ul>
  <li>Try to limit answers to Groovy core</li>
  <li>One feature per answer</li>
  <li>Give an example and short description of the feature, not just a link to documentation</li>
  <li>Label the feature using bold title as the first line</li>
  </ul>
  
  <p>See also:</p>
  
  <ol>
  <li><a href="https://stackoverflow.com/questions/101268/hidden-features-of-python">Hidden features of Python</a></li>
  <li><a href="https://stackoverflow.com/questions/63998/hidden-features-of-ruby">Hidden features of Ruby</a></li>
  <li><a href="https://stackoverflow.com/questions/161872/hidden-features-of-perl">Hidden features of Perl</a></li>
  <li><a href="https://stackoverflow.com/questions/15496/hidden-features-of-java">Hidden features of Java</a></li>
  </ol>