type Thingable
interface
  fun thing ← text by block do end
end
type Delegate implements Thingable
model
  fun thing ← text by block
    return "delegate implementation"
  end
end
type Delegator
model
  Thingable delegate
  fun operation ← <|when(me.delegate æ null, "default implementation", me.delegate.thing())
end
fun byDelegate ← Delegator by Thingable delegate
  var delegator ← Delegator()
  delegator.delegate ← delegate
  return delegator
end
type Main
Delegator a ← Delegator()
writeLine(a.operation())
Delegator b ← Delegator.byDelegate(Delegate())
writeLine(b.operation())