title: Ugettext_lazy as dictionary key in django
body: <p>Why the following code doesn't work?</p>
  
  <p>Is it possible to use proxy objects as keys?</p>
  
  <pre><code>from django.utils.translation import ugettext_lazy as _
  
  ABBREVIATIONS = {
      _('tr.'): 'transitive'
  }
  </code></pre>