func (ivt *IntervalTree) MaxHeight() int {
	return int((2 * math.Log2(float64(ivt.Len()+1))) + 0.5)
}
func (ivt *IntervalTree) MaxHeight() int {
	return int((2 * math.Log2(float64(ivt.Len()+1))) + 0.5)
}
// MaxHeight is the expected maximum tree height given the number of nodes