[$] Python dictionary "addition" and "subtraction"

A proposal to add a new dictionary operator for Python has spawned a PEP
and two large threads on the python-ideas mailing list. To a certain
extent, it is starting to look a bit like the 'PEP 572 mess'; there are plenty of opinions on
whether the feature should be implemented and how it should be spelled, for
example. As yet, there has been no formal decision made on how the new steering council will be handling PEP
pronouncements, though a review
of open PEPs is the council's
'highest priority'. This PEP will presumably be added into
the process; it is likely too late to be included in Python 3.8 even
if it were accepted soon,
so there is plenty of time to figure it all out before 3.9 is released
sometime in 2021.