> Are typing.ChainMap and others actually abstract classes?

They are abstract classes in the sense that they are instances of abc.ABCMeta. However, for some reasons inspect checks __flags__ attribute. The latter probably reflects the fact that Deque etc. do not have abstract methods (they still need to be instances of abc.ABCMeta because they need to be generic).

I don't think that we need to change behaviour of inspect because it could be backward incompatible. I would either make changes to refleak or typing (adding few more cleanups in either place).