docs: function _initChildren() {
      if (!this._children) {
        return;
      }
      for (var child in this._children) {
        var childAttrs = this._attrs && this._attrs[child] ? this._attrs[child] : {};
        this[child] = new this._children[child](childAttrs, { parent: this, parse: true });
        this.listenTo(this[child], 'all', this._getEventBubblingHandler(child));
      }
    }