abstract class AbstractCurrency[Currency <: AbstractCurrency[Currency]](val amount: Long) {
  val designation: String
  
  def make(amount: Long): Currency
  
  def +(that: Currency) = make(amount + that.amount)
  
  def *(x: Double) = make((amount * x).toLong)
  
  override def toString = amount + " " + designation
}

class Example[T <: Inner] {
  class Inner {}
}