Events as Python sets

You will write three functions that build new events from two old ones: the union, the outcomes in exactly one of the two events, and the outcomes in neither. The checker uses the outcomes of two dice.

The idea. An event is a set of outcomes, and Python sets have the same operations. a | b is the union, a & b the intersection and a - b the difference. Subtract from the whole space to get a complement.

Your tasks.

1. Finish either(a, b). Return the outcomes that are in a or in b or in both.
2. Finish exactly_one(a, b). Return the outcomes that are in a or in b but not in both.
3. Finish neither(space, a, b). Return the outcomes of space that are in neither event.