title: Ruby delete method (string manipulation)
body: <p>I'm new to Ruby, and have been working my way through Mr Neighborly's Humble Little Ruby Guide. There have been a few typos in the code examples along the way, but I've always managed to work out what's wrong and subsequently fix it - until now!</p>
  
  <p>This is really basic, but I can't get the following example to work on Mac OS X (Snow Leopard):</p>
  
  <pre><code>gone = "Got gone fool!"
  puts "Original: " + gone
  gone.delete!("o", "r-v")
  puts "deleted: " + gone
  </code></pre>
  
  <p>Output I'm expecting is:</p>
  
  <pre><code>Original: Got gone fool!
  deleted: G gne fl!
  </code></pre>
  
  <p>Output I actually get is:</p>
  
  <pre><code>Original: Got gone fool!
  deleted: Got gone fool!
  </code></pre>
  
  <p>The delete! method doesn't seem to have had any effect.</p>
  
  <p>Can anyone shed any light on what's going wrong here? :-\</p>