title: How to inject service to angular constant
body: <p>I would like to define a constant which use <code>$locale</code> service. Constants are objects, so I can't inject it as parameter as in case of controller. How can I use it?</p>
  
  <pre><code>angular.module('app').constant('SOME_CONSTANT', {
    'LOCALE': $locale.id.slice(0, 2)
  })
  </code></pre>