To install a package and its dependencies, you need the list of dependencies. This metadata is not always statically available!

Python packages are often just a zip file full of py files, with one of them called 'setup.py'. Running this file installs the package (originally using [distutils](https://docs.python.org/3.9/install/index.html#install-index)). This installation may fail if dependencies are not present, but there’s no method provided for installing those dependencies. You’re supposed to read the error message, go download the source for the missing dependencies, then run their setup.py scripts to install them.