网络爬虫系列视频：
https://edu.csdn.net/course/detail/28645
Requests库的head()方法主要用于获取HTML网页头信息，相当于HTTP的HEAD。例如，抓取百度首页的头部信息，示例代码如下：
{‘Cache-Control’: ‘private, no-cache, no-store, proxy-revalidate, no-transform’, ‘Connection’: ‘keep-alive’, ‘Content-Encoding’: ‘gzip’, ‘Content-Type’: ‘text/html’, ‘Date’: ‘Sat, 18 Apr 2020 10:24:26 GMT’, ‘Last-Modified’: ‘Mon, 13 Jun 2016 02:50:05 GMT’, ‘Pragma’: ‘no-cache’, ‘Server’: ‘bfe/1.0.8.18’}