LFtools requires python3 (3.6+) virtual environment. https://virtualenv.pypa.io/en/stable/. Not using a virtualenv can have serious negative side effects!
LFTools is available on pypi. LFtools has migrated to python3, ensure python3 is available your system. To install LFTools, create a virtualenv, with pip3 install lftools in your shell.
Often during development you want to run tests and/or try code out locally as you change it. To do this you need the installation of LFTools to be your local git repo. After doing pip3 install -r requirements.txt issue the command pip3 install -e .