urllib2和urllib3是并存关系还是代替关系？
pip install urllib2不能安装:
C:\Users\dell\AppData\Local\Programs\Python\Python35>pip install urllib2
Collecting urllib2
Could not find a version that satisfies the requirement urllib2 (from versions: )
No matching distribution found for urllib2
Python3 urllib2和urllib合并了
至于urllib3是一个第三方库