title: replace strings n times, starting from the end
body: <p>It is my second day with golang, I'll probably ask a very basic question:</p>
  
  <p>I want to replace parts of a string, that is what <a href="http://golang.org/pkg/strings/#Replace" rel="nofollow">strings.Replace</a> is good for:</p>
  
  <pre><code>func Replace(s, old, new string, n int) string
  </code></pre>
  
  <p>The last parameter is the number of times <code>old</code> gets replaced by <code>new</code> - starting from the beginning of the string.</p>
  
  <p>Is there a similar standard function that starts from the end?</p>