title: Identifying multiple joysticks in Pyglet
body: <p>I'm making a game which may use one or two identical (i.e. same manufacturer and model name) joysticks with Pyglet. The game would save the key config in a file, but it's unable to distinguish, e.g. <code>START</code> button from left or right one.</p>
  
  <p>I found a class named <code>pyglet.input.darwin_hid.PygletDevice</code> and its instance <code>device_identifier</code>, but the module seems to be prohibited from <code>import</code>ing...</p>
  
  <p>Is there any way to identify the joysticks without using this, or to make this module <code>import</code>able?</p>