Multiply.scala

case class Multiply(first: Component, second: Component) extends Component {
  override def toTree(implicit c: blackbox.Context): c.Tree = {
    import c.universe._
    q"${first.toTree} * ${second.toTree}"
  }

  override def derive: Component =
    Add(
      Multiply(first, second.derive),
      Multiply(first.derive, second)
    )
}