# Return the C symbol associated to a live type runtime
	# REQUIRE: self.runtime_type_analysis.live_types.has(mtype)
	fun classid(mtype: MClassType): String
	do
		if self.classids.has_key(mtype) then
			return self.classids[mtype]
		end
		print_error "No classid for {mtype}"
		abort
	end