code: function(name, callback, options) {
        options = options || {};
        this._events = this._events || {};
        this._events[name] = this._events[name] || [];
  
        var subscription = {
          callback : callback,
          priority : options.priority || 0,
          token : options.token || _.uniqueId("t"),
          context : options.context || this
        };
        var position;
        _.each(this._events[name], function(event, index) {
          if (!_.isUndefined(position)) { return; }
          if (event.priority <= subscription.priority) {
            position = index;
          }
        });
  
        this._events[name].splice(position, 0, subscription);
        return subscription.token;
      }
docs: Allows subscribing on an evented object to a specific name.
  Provide a callback to trigger.
  Params:
  name - event to subscribe to
  callback - callback to trigger
  options - optional arguments
  priority - allows rearranging of existing callbacks based on priority
  context - allows attaching diff context to callback
  token - allows callback identification by token.