title: Python how to override a method defined in a module of a third party library
body: <p>I've installed a third party library <a href="http://www.tornadoweb.org" rel="noreferrer">tornado</a> by <strong>pip</strong> and need to override a <strong>method</strong>, say <code>to_unicode</code> defined in the global scope of a module say <code>tornado.escape</code>. So that all calls to that method will use my overridden version. Or maybe, I would want to control it so that only my code will use the overridden version. </p>
  
  <p>If it had been defined inside a class, I'd have no problem to subclass it and override the method! But since this is just a method, I'm wondering how to override it.</p>
  
  <p>Surprisingly, I found not suitable solution in SO, is this kind of impossible to achieve? </p>