cofreeCataM.scala

    @inline final def cataM[F[_] : Traverse, M[_] : Monad, A, B]
    (tf: Cofree[F, A])(destroy: (A, F[B]) => M[B]): M[B] = {
      val head: A = tf.head
      val tail: F[Cofree[F, A]] = tf.tailEval.value
      val looped: M[F[B]] = tail.traverse(cataM(_)(destroy))
      val destroyed: M[B] = looped.flatMap(destroy(head, _))
      destroyed
  }