trait PaymentableMapper[OwnerType <: PaymentableMapper[OwnerType]] extends LongKeyedMapper[OwnerType] {
    self: OwnerType =>
    def paid: Unit
}

trait PaymentableMetaMapper[OwnerType <: PaymentableMapper[OwnerType]] extends LongKeyedMetaMapper[OwnerType] {
    self: OwnerType =>
}


class Payment extends LongKeyedMapper[Payment] with IdPK {
    object paymentable extends MappedLongForeignKey(this, PaymentableMetaMapper)
}