code: function (els) {
      var key;
      var i;
      var objects = this.objects;
  
      // Push meshes and other attachments onto list of objects to intersect.
      objects.length = 0;
      for (i = 0; i < els.length; i++) {
        if (els[i].isEntity && els[i].object3D) {
          for (key in els[i].object3DMap) {
            objects.push(els[i].getObject3D(key));
          }
        }
      }
  
      return objects;
    }
docs: Return A-Frame attachments of each element's object3D group (e.g., mesh).
  Children are flattened by one level, removing the THREE.Group wrapper,
  so that non-recursive raycasting remains useful.
  
  Only push children defined as component attachemnts (e.g., setObject3D),
  NOT actual children in the scene graph hierarchy.
  
  @param  {Array<Element>} els
  @return {Array<THREE.Object3D>}