如果有其他的需求，请参考[el-table](http://element-cn.eleme.io/#/en-US/component/table)的 api 自行修改 index.vue
This component only provides a solution for creating `TreeTable`. It is based on the `element-ui` table component. It uses the `row-style` method of `el-table` to determine whether the element needs to be hidden or displayed.
And this component makes full use of the features of the `vue` slot to make it user-friendly.
In `evel.js`, the `addAttrs` method adds several properties to the data, and `treeTotable` flattens the array. None of these operations will destroy the source data, just add properties.