PEP 660, a Python specification I worked on, has been accepted. It helps to make Python distributions importable during development; this is called an ‘editable’ installation. Today `pip install -e` calls `setup.py develop`. This specification exposes similar functionality without having to provide `setup.py`. Since `pip` takes care of the actual installation it is easier for a new build system to implement. Arbitrary build systems will finally be on the same footing as setuptools.