code: function(feature) {
  
          var interactive = joint.util.isFunction(this.options.interactive)
              ? this.options.interactive(this)
              : this.options.interactive;
  
          return (joint.util.isObject(interactive) && interactive[feature] !== false) ||
                  (joint.util.isBoolean(interactive) && interactive !== false);
      }
docs: Return `true` if cell link is allowed to perform a certain UI `feature`. Example: `can('vertexMove')`, `can('labelMove')`.