create python 2.7 virtual environment code example

Example 1: how to create a new virtualenv

to make a new virtualenv: 
virtualenv env_name

             to activate this virtual environment:
source env_name/bin/activate (on mac and linux)
source env_name/Scripts/activate (on windows)

Example 2: create a virtual environment python 3

python3 -m venv /path/to/new/virtual/environment

Example 3: how to use virtual environment python

python3 -m pip install --user virtualenv

Example 4: how to make virtual environment

virtualenv mypython