code: function(path, opt) {
  
          // Once a property is removed from the `attrs` attribute
          // the cellView will recognize a `dirty` flag and rerender itself
          // in order to remove the attribute from SVG element.
          opt = opt || {};
          opt.dirty = true;
  
          var pathArray = Array.isArray(path) ? path : path.split('/');
  
          if (pathArray.length === 1) {
              // A top level property
              return this.unset(path, opt);
          }
  
          // A nested property
          var property = pathArray[0];
          var nestedPath = pathArray.slice(1);
          var propertyValue = joint.util.cloneDeep(this.get(property));
  
          joint.util.unsetByPath(propertyValue, nestedPath, '/');
  
          return this.set(property, propertyValue, opt);
      }
docs: A convient way to unset nested properties