The term 'python3' is not recognized as the name of a cmdlet code example

Example: 'python3' is not recognized as an internal or external command,

There is no python3.exe file, that is why it fails.

Try:

py

instead.

py is just a launcher for python.exe. If you have more than one python versions installed on your machine (2.x, 3.x) you can specify what version of python to launch by

py -2 or py -3