${countries[treeSelected].name}
${countries[v].name}
```html
<ui-tree options[bindable]="UITreeOptions" model[bindable]="UITreeModel"
value[bindable]="string"></ui-tree>
```
* UITreeOptions
- `showCheckbox`: Checkable items
- `checkboxLevel`: Checkable tree level. -1 to have all levels checkable.
- `showRoot`: Display root node
- `rootLabel`: Root node label
- `selectionLevel`: Selectable tree level. -1 to have all levels selectable.
* UITreeModel
- `id`
- `text`
- `icon`
- `leaf`
- `checked`
- `disabled`
- `expanded`
- `children`: `Array<UITreeModel>`