demo/amd/rjs/output/unified/marionette-build.js
function(child, ChildView, index) {
      var childViewOptions = this.getOption('childViewOptions');
      childViewOptions = Marionette._getValue(childViewOptions, this, [child, index]);
  
      var view = this.buildChildView(child, ChildView, childViewOptions);
  
      // increment indices of views after this one
      this._updateIndices(view, true, index);
  
      this.triggerMethod('before:add:child', view);
      this._addChildView(view, index);
      this.triggerMethod('add:child', view);
  
      view._parent = this;
  
      return view;
    }
function(child, ChildView, index) {
      var childViewOptions = this.getOption('childViewOptions');
      childViewOptions = Marionette._getValue(childViewOptions, this, [child, index]);
  
      var view = this.buildChildView(child, ChildView, childViewOptions);
  
      // increment indices of views after this one
      this._updateIndices(view, true, index);
  
      this.triggerMethod('before:add:child', view);
      this._addChildView(view, index);
      this.triggerMethod('add:child', view);
  
      view._parent = this;
  
      return view;
    }
Render the child's view and add it to the HTML for the collection view at a given index. This will also update the indices of later views in the collection in order to keep the children in sync with the collection.