mono.go
func Monotonic() time.Duration {
	sec, nsec := monotime()
	return time.Duration(sec*1000000000 + int64(nsec))
}
func Monotonic() time.Duration {
	sec, nsec := monotime()
	return time.Duration(sec*1000000000 + int64(nsec))
}
// Monotonic returns a time duration from some fixed point in the past.