Thinking系列，旨在利用10分钟的时间传达一种可落地的编程思想。
echarts 中如何将 legend 设置成「直线」？
所有图例均为直线
可以通过 itemHeight 和 itemWidth 来统一控制
legend: {itemHeight: 2,itemWidth: 20,data: ['Expenses', 'Income']}
部分是直线
需要通过icon+base64图片来实现
legend: {itemHeight: 20,itemWidth: 20,data: [{name: 'Expenses',icon: 'react'}, {name: 'Income',icon: 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按照第一种方式生成直线类型，然后截图，通过在线工具转base64.
