It's safe to upcast integer types to Long,
floating-point types to Double.
So we don't have to create a range instance for cases such as
fun testLongInInt(x: Long, a: Int, b: Int) =
x in a .. b
which is equivalent to
fun testLongInInt(x: Long, a: Int, b: Int) =
x in a.toLong() .. b.toLong()
