his doesn't work
      (probably from having done it before), I invite you to quickly
      create a simple text file called "input_file" containing
      the sentence
   </p><pre class="programlisting">
      The quick brown fox jumped over the lazy dog.</pre><p>surrounded by blank lines.  Code it up and try it.  The contents
      of "output_file" may surprise you.
   </p><p>Seriously, go do it.  Get surprised, then come back.  It's worth it.
   </p><p>The thing to remember is that the <code class="code">