``` const treeState = { name: 'root [half checked and opened]', checked: 0.5, // half check: some children are checked isOpen: true, // this folder is opened, we can see it's children children: [ { name: 'children 1 [not checked]', checked: 0 }, { name: 'children 2 [half checked and not opened]', checked: 0.5, isOpen: false, isDisabled: true, // <--- add this optional property to disable the checkbox children: [ { name: 'children 2-1 [not checked]', checked: 0, isDisabled: true }, { name: 'children 2-2 [checked]', checked: 1 }, ], }, ], }; ```