raise MaxRetryError(_pool, url, error or ResponseError(cause))
pip._vendor.urllib3.exceptions.MaxRetryError: HTTPSConnectionPool(host=‘files.pythonhosted.org’, port=443): Max retries exceeded with url: /packages/f2/94/3af39d34be01a24a6e65433d19e107099374224905f1e0cc6bbe1fd22a2f/argparse-1.4.0-py2.py3-none-any.whl (Caused by ProtocolError(‘Connection aborted.’, OSError(107, ‘传输端点尚未连接’)))

镜像不可用，网络不可达。

在用pip安装的时候，添加国内镜像

例如：原本执行的命令是：
pip3 install argparse psutil pygresql pyyaml
pip3 install argparse psutil pygresql pyyaml -i http://pypi.douban.com/simple/ --trusted-host pypi.douban.com
参考https://www.cnblogs.com/mabingxue/p/8872365.html
				
使用selenuim报错  raise MaxRetryError(_pool, url, error or ResponseError(cause))
urllib3.exceptions.MaxRetryError: HTTPConnectionPool(host=‘127.0.0.1’, port=53643): Max retries exceeded with url: /session/3ce406f838f141e6d386e6532f7bfa7f/element/fb4d42b8-ce35-
				
Traceback (most recent call last):
  File "D:\Anaconda3\lib\site-packages\urllib3\connectionpool.py", line 601, in urlopen
    chunked=chunked)
  File "D:\Anaconda3\lib\site-packages\urllib3\connectio...
 File "/usr/local/lib/python2.7/dist-packages/urllib3/util/retry.py", line 446, in increment
  raise MaxRetryError(_pool, url, error or ResponseError(cause))
urllib3.exceptions.MaxRetryError: HTTPSConnectionPool(ho...
headers = {
    'User-Agent': 'Mozilla/5.0 (Windows NT 6.1; WOW64) '
                  'AppleWebKit/537.36 (KHTML, like Gecko)'
                  ' Chrome/63.0.3239.132 Safari/537.36...
Traceback (most recent call last):
  File "F:\project\venv\lib\site-packages\urllib3\connectionpool.py", line 594, in urlopen
    self._prepa...
Traceback (most recent call last):
  File "E:\Anaconda\lib\site-packages\urllib3\connectionpool.py", line 588, in urlopen
    conn = self._get_conn(timeout=pool_timeout)
  File "E...