// that must be published when publishing from a tree of
// size newTreeSize to replace a tree of size oldTreeSize.
// (No tiles need to be published for a tree of size zero.)
//
// If h ≤ 0, NewTiles panics.
func NewTiles(h int, oldTreeSize, newTreeSize int64) []Tile {
	if h <= 0 {
		panic(fmt.Sprintf("NewTiles: invalid height %d", h))
	}
	H := uint(h)
	var tiles []Tile