code: func Same(t1, t2 *tree.Tree) bool {
  	w1, w2 := make(chan int), make(chan int)
  	quit := make(chan int)
  	defer close(quit)
  
  	go Walk(t1, w1, quit)
  	go Walk(t2, w2, quit)
  
  	for {
  		v1, ok1 := <-w1
  		v2, ok2 := <-w2
  		if !ok1 || !ok2 {
  			return ok1 == ok2
  		}
  		if v1 != v2 {
  			return false
  		}
  	}
  }
docs: // Same determines whether the trees
  // t1 and t2 contain the same values.