It came to my attention that:

In the original PEP True and False are said to be singletons https://www.python.org/dev/peps/pep-0285/, but it's not in the Data Model https://docs.python.org/3/reference/datamodel.html

This came to my attention by code wanting to own the valid values in a dict's key:

if settings[MY_KEY] is True:
...

If True and False are singletons in the spec (and not only in the CPython implementation), it should be prominent and well known.

Cheers,

Juancarlo Añez