适合element ui 的全国城市三级联动json数据，包含编码，{
value: '110000',
label: '北京市',
children: [{
value: '110100',
label: '北京市',
children: [
{ value: '110101', label: '东城区' },
{ value: '110102', label: '西城区' },
{ value: '110105', label: '朝阳区' },
{ value: '110106', label: '丰台区' },
{ value: '110107', label: '石景山区' },
{ value: '110108', label: '海淀区' },
{ value: '110109', label: '门头沟区' },
{ value: '110111', label: '房山区' },
{ value: '110112', label: '通州区' },
{ value: '110113', label: '顺义区' },
{ value: '110114', label: '昌平区' },
{ value: '110115', label: '大兴区' },
{ value: '110116', label: '怀柔区' },
{ value: '110117', label: '平谷区' },
{ value: '110118', label: '密云区' },
{ value: '110119', label: '延庆区' }
]
}]
}
