code: function loadFromIconSet(id) {
      var setName = id.substring(0, id.lastIndexOf(':')) || '$default';
      var iconSetConfig = config[setName];
  
      return !iconSetConfig ? announceIdNotFound(id) : loadByURL(iconSetConfig.url).then(extractFromSet);
  
      function extractFromSet(set) {
        var iconName = id.slice(id.lastIndexOf(':') + 1);
        var icon = set.querySelector('#' + iconName);
        return icon ? new Icon(icon, iconSetConfig) : announceIdNotFound(id);
      }
  
      function announceIdNotFound(id) {
        var msg = 'icon ' + id + ' not found';
        $log.warn(msg);
  
        return $q.reject(msg || id);
      }
    }
docs: Loads the file as XML and uses querySelector( <id> ) to find the desired node...
  @param {string} id icon id in icon set
  @returns {angular.$q.Promise}