Install and run python applications in isolated environments.

# To run an app in a temporary virtual environment:
pipx run <pycowsay> <moo>

# To install a package in a virtual environment and add entry points to path:
pipx install <package>

# To list installed packages:
pipx list

# To run an app in a temporary virtual environment with a pakage name different from the executable:
pipx run --spec <httpx-cli> <httpx> <http://www.github.com>