I don't know if there's a ticket, but one way to fix it is to make the
following two lines of parent.Parent.__init__
else:
category = Category.join((category, Sets().Facades()))
into
if category is None:
category = Sets().Facades()
Hello,
There is a weirdness in the initialization of Parent with a facade.
Consider the following example
class MySet(Parent):
def __init__(self):
Parent.__init__(self, category=(FiniteEnumeratedSets(), Monoids()))
The category of an instance of MySet is just a join of the two
catego
