interface IVehicle

	get mpg as decimal


interface ICar
	inherits IVehicle

	get hasAirBags as bool


class Test

	def main is shared
		pass

	def describe(car as ICar)
		print car.hasAirBags
		print car.mpg  # used to generate false error: Cannot find a definition for "mpg" in "car" whose type is "ICar".  Token text is "mpg"