Python dictionary "addition" and "subtraction"

But if there is support, I'd argue strongly against using + and - operators. This is far more likely to lead to accidents than using |. This latter operator is far less frequently used, and seeing it always alerts one to the fact that something out of the ordinary is going on. Also one can visualize a set as a dict where all values are the same and irrelevant, such as True. In fact back before we had sets, that's what we used to do. So extending the set | operator to apply similarly to dicts makes reasonable sense.

Subtraction I like even less. Non-commutativity I can live with, but subtraction completely ignores the values in the dict being "Subtracted". A much better idea would be a dict.subtract( other) method.