code: function(element, opt) {
  
          opt = joint.util.defaults(opt || {}, { searchBy: 'bbox' });
  
          var bbox = element.getBBox();
          var elements = (opt.searchBy === 'bbox')
              ? this.findModelsInArea(bbox)
              : this.findModelsFromPoint(bbox[opt.searchBy]());
  
          // don't account element itself or any of its descendents
          return elements.filter(function(el) {
              return element.id !== el.id && !el.isEmbeddedIn(element);
          });
      }
docs: Find all elements under the given element.