Windows switch between python 2 and 3

[Daiyue Weng]

Hi, I installed Python 2.7 and Python 3.5 64 bit versions on Win 10. Under

C:\Python35

C:\Python27

Both have been set in environment variable Path.

When I type python in cmd, it only gives me python 2.7, I am wondering how
to switch between 2 and 3 in command prompt.

cheers