bad-power-plant.scala

import scala.concurrent.Future

trait WaterSupply {
  def turnOn(): Future[Unit]
}

trait PowerPlant {
  def waterSupply: WaterSupply
  
  def increaseVolumeControl(): Future[Boolean]

  def turnOn(): Future[Boolean] = {
    waterSupply.turnOn()
    increaseVolumeControl()
  }
}