install pyserial

[snippsat]

In cmd:

C:\>python -V
Python 3.7.3

C:\>python -c "import sys; print(sys.executable)"
C:\python37\python.exe

C:\>pip -V
pip 19.1.1 from c:\python37\lib\site-packages\pip (python 3.7)

See that pip -V is pointing to python 3.7.
This men that doing pip install pyserial will only install to python 3.7.

C:\>pip install pyserial
Collecting pyserial
  Downloading https://files.pythonhosted.org/packages........
Installing collected packages: pyserial
Successfully installed pyserial-3.4

# Test that it work
C:\>python
Python 3.7.3 (v3.7.3:ef4ec6ed12, Mar 25 2019, 21:26:53) [MSC v.1916 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import serial
>>>
>>> serial.__version__
'3.4'
>>> exit()

C:\>