title: What is the difference between using partial and not using partial for tornado.options.define?
body: <p>I see two ways of setting up define in tornado.</p>
  
  <pre><code>import tornado.options
  def define_web(hidden=False):
  
      define = partial(tornado.options.define, group='Web', hidden=hidden)
      define('thread', False, type=bool,
          help='threading')
  </code></pre>
  
  <p>and without using partial</p>
  
  <pre><code>from tornado.options import options, define
  
  def define_web(hidden=False):
      define('thread', False, type=bool,
          help='threading')
  </code></pre>
  
  <p>So I was wondering what is the difference, and what is advantage of using partials</p>