Scala Universal Set

gistfile1.scala

class UniversalSet[A] extends Set[A] {
  def contains(key: A) = true
  def iterator = throw new UnsupportedOperationException()
  def +(elem: A) = this
  def -(elem: A) = throw new UnsupportedOperationException()
  override def toString: String = "UniversalSet"
}

This is a bare minimum implementation. There are likely several other methods/traits I need to implement to make this usable, for example isEmpty(). In fact, any of the mixed-in methods that rely on iterator will error.