string(339) "get document error：https://zhidao.baidu.com/search?lm=0&rn=10&pn=0&fr=search&dyTabStr=null&word=%E5%9F%BA%E5%B0%BC%E7%B3%BB%E6%95%B0%E7%9A%84%E5%AE%9A%E4%B9%89%E6%BA%90%E4%BA%8E%E5%87%A0%E4%B8%AA%E5%8F%98%E9%87%8F%E7%9A%84%E7%BD%97%E4%BC%A6%E6%AC%A1%E6%9B%B2%E7%BA%BF => Failed to connect to 101.89.117.144 port 38005: Connection refused"
基尼系数的定义源于几个变量的罗伦次曲线
