tree-data

[{
    label: '一级 1',
    children: [{
      label: '二级 1-1',
      children: [{
        label: '三级 1-1-1'
      }]
    }]
  },
  {
    label: '一级 2',
    children: [{
      label: '二级 2-1',
      children: [{
        label: '三级 2-1-1'
      }]
    }, {
      label: '二级 2-2',
      children: [{
        label: '三级 2-2-1'
      }]
    }]
  },
  {
    label: '一级 3',
    children: [{
      label: '二级 3-1',
      children: [{
        label: '三级 3-1-1'
      }]
    }, {
      label: '二级 3-2',
      children: [{
        label: '三级 3-2-1'
      }]
    }]
  }
]