the simplest possible translation unit. seeds the eight primitive
types and registers a single, empty `main` function.

<<<

main = fun () {
}

>>>

(unit
	(types
		(type 0 int primitive)
		(type 1 uint primitive)
		(type 2 bool primitive)
		(type 3 string primitive)
		(type 4 float primitive)
		(type 5 byte primitive)
		(type 6 ascii primitive)
		(type 7 void primitive))
	(functions
		(function 0 main main (returns (ref void)) (block)))
	(emission_order 0 1 2 3 4 5 6 7))