不同节点中元素的序号值

Question

基于计数位于不同节点的元素名称。我想给出唯一但序列号。  输入数据

<record>
    `enter code here` <items>
        <list code="a">  item location </list>
        <list code="b"> 123 </list>
     </items>
    <items>
        <list code="a">  item location </list>
        <list code="b"> 123 </list>
     </items>
</record>

期望的输出

<record>
     <items>
        <list code="a">  item location </list>
        <list code="b">1 </list>
     </items>
    <items>
        <list code="a">  item location </list>
        <list code="b"> 2 </list>
     </items>
</record>