Use pipx to:
install and run Python applications insolated environments.
In particular, it's a safe way to "globally" install and manage Python tools that you don't want to pollute your system or project virtualenvs.
Install on MacOS:
brew install pipx
pipx ensurepath
WARNING: pipx only supports Python 3 tools, not version 2 tools.
Sometimes python2 tools seem to install okay with pipx but will fail with
strange errors when you run them (e.g. thumbor)