<chart palette="2" caption="Unit Sales" xAxisName="Month" yAxisName="Units" showValues="0" decimals="0" formatNumberScale="0" useRoundEdges="1">
 
 
<set label="Jan" value="462" /> 
<set label="Feb" value="857" /> 
 
<set label="Mar" value="671" /> 
<set label="Apr" value="494" /> 
 
<set label="May" value="761" /> 
<set label="Jun" value="960" /> 
</chart>
 怎么解析节点set的属性label和value?