virtualenv is a tool to create isolated Python environment

• Install it via apt-get:

$ sudo apt-get install python3-venv

• traverse to the project folder
• create a virtual environment in current directory

$ virtualenv venv

• this creates a copy of Python in whichever directory you ran the command in, placing it in a folder named venv.
• to begin using the virtual environment, it needs to be activated

$ source venv/bin/activate

• install any new modules without affecting system default Python or other virtual environments using pip/pip3
• generate requirements.txt

$ pip3 freeze > requirements.txt

• if you are done working in the virtual environment , you can deactivate it

$ deactivate

• to delete a virtual environment, just delete its folder venv