title: What does Gulp "done" method do?
body: <p>Just a simple question to clarify what does parameter <code>"done"</code> in a gulp task do?</p>
  
  <p>I understand, this is the callback in task function as shown below.</p>
  
  <pre><code>gulp.task('clean', function(done) {
      // so some stuff
      creategulptask(cleantask(), done);
  });
  </code></pre>
  
  <p>But what is the reason to pass it?</p>