section_div.scala

class Foo(x: Int) {
  val v = x
  def +(y: Foo) = new Foo(v + y.v)
  def less(y: Foo) = v < y.v
}

val a = new Foo(1) + new Foo(2)
val b = new Foo(1) less new Foo(2)
println(a.v) // 3
println(b) // true