Some types have a finite number of possible inhabitants. Examples include builtins.bool (the inhabitants are Literal[True] and Literal[False]) and enum types. For such types, we should consider the union of all possible inhabitants as equivalent to the type itself (so for example Literal[True, False]) is equivalent to builtins.bool). We should also take this equivalence into account when resolving negated intersections (so for example builtins.bool & ~Literal[True] is equivalent to Literal[False]; practically this will come up in type narrowing.)

Tasks here, in the order we'll likely get to them:

• resolve Literal[True] | Literal[False] to builtins.bool
• resolve builtins.bool back to Literal[True] | Literal[False] when intersection eliminates a type inhabitant
• extend the above handling to enum types, when we add them