无法安装socketIO-client

Question

我正在尝试通过WebSocket启用通信。为此，我正在使用socketIO-client。我在虚拟环境'virtualenv'中，并且在终端中使用命令pip install -U socketIO-client==0.7.2，但是我看到此错误。

(.virtualenv)pi@raspberrypi:~ $ pip install -U socketIO-client==0.7.2
Cannot fetch index base URL https://pypi.python.org/simple/
Could not find any downloads that satisfy the requirement socketIO-client==0.7.2 in ./.virtualenv/lib/python2.7/site-packages
Downloading/unpacking socketIO-client==0.7.2
Cleaning up...
No distributions at all found for socketIO-client==0.7.2 in ./.virtualenv/lib/python2.7/site-packages
Storing debug log for failure in /home/pi/.pip/pip.log

我应该如何安装socketIO-client？

PS：我也尝试过pip install -U socketIO-client，它显示了相同的错误。 我正在关注这个link