Project dosen't use virtual env for dependency management
virtualenv is used to manage Python packages for different projects. Using virtualenv allows you to avoid installing Python packages globally which could break system tools or other projects. You can install virtualenv using pip.
This project doesn't use a virtual environment which creates a problem with dependency resolution while developing. Generally, it's a good idea to keep our development environment separated from others.
See here for more info: https://packaging.python.org/en/latest/guides/installing-using-pip-and-virtual-environments/#installing-packages-using-pip-and-virtual-environments