title: What are the Ruby's Object#taint and Object#trust methods?
body: <p>I was reading about Ruby string methods in the <a href="http://www.ruby-doc.org/core-1.9.3/String.html" rel="noreferrer">docs</a> and came accross the methods </p>
  
  <ul>
  <li><code>taint</code></li>
  <li><code>trust</code></li>
  <li><code>untaint</code></li>
  <li><code>untrust</code></li>
  </ul>
  
  <p>I don't know what they do, which situation do we use them? Has anyone used any of them? Examples would be nice.</p>