panic("tlog: bad math in leafProofIndex")
	}
	if lo+1 == hi {
		return need
	}
	if k, _ := maxpow2(hi - lo); n < lo+k {
		need = leafProofIndex(lo, lo+k, n, need)
		need = subTreeIndex(lo+k, hi, need)
	} else {
		need = subTreeIndex(lo, lo+k, need)
		need = leafProofIndex(lo+k, hi, n, need)
	}
	return need
}