Cannot open file [ERNO 22] INVALID ARGUMENT

[snippsat]

Add Python to Windows PATH Environment as mention.
You add:

C:\Python27\
C:\Python27\Scripts

Then in path it look like this C:\Python27\;C:\Python27\Scripts\;
Restart PC.

Now should python work from anywhere in cmd like this.

Microsoft Windows [Version 10.0.15063]
(c) 2017 Microsoft Corporation. Med enerett.

C:\Windows\System32>cd\

C:\>python
Python 3.6.2 (v3.6.2:5fd33b5, Jul  8 2017, 04:14:34) [MSC v.1900 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> exit()

C:\>py -2.7
Python 2.7.9 (default, Dec 10 2014, 12:24:55) [MSC v.1500 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> exit()

C:\>

You should see python 2.7 start opp from root C:\ or anywhere in cmd.