why do you want a virtual environment for python code example

Example 1: how to set up python virtual environment

# install the package virtualenv
pip install virtualenv

# setup envioronment for Data engineering pipeline
virtualenv dataengineer_pipeline

# if using python >= 3.3
python -m venv dataengineer_pipeline

# start the environment in linux using 
dataengineer_pipeline/bin/activate

# or in windows
dataengineer_pipeline\Scripts\activate.bat

# when you are done using the environment, type in the command below
deactivate

Example 2: how virtual environment in python works

>>> import sys
>>> sys.prefix
'/System/Library/Frameworks/Python.framework/Versions/3.5'