code: def primary_avatar(user, size=settings.AVATAR_DEFAULT_SIZE):
      
      alt = six.text_type(user)
      url = reverse('avatar_render_primary', kwargs={'user': user, 'size': size})
      return ("""<img src="%s" alt="%s" width="%s" height="%s" />""" %
              (url, alt, size, size))
docs: This tag tries to get the default avatar for a user without doing any db
      requests. It achieve this by linking to a special view that will do all the
      work for us. If that special view is then cached by a CDN for instance,
      we will avoid many db calls.