PEP 517 specifies a standard API for systems which build Python packages.
PEP 660 extends it with a build mode that leads to editable installs.

This package contains wrappers around the hooks specified by PEP 517 and
PEP 660. It provides:

- A mechanism to call the hooks in a subprocess, so they are isolated
from the current process.

- Fallbacks for the optional hooks, so that frontends can call the hooks
without checking which are defined.
