func OSub(a uint64, b uint64) (res uint64, overflowed bool) {
	res = a - b
	overflowed = res > a
	return
}
OSub subtracts b from a with overflow detection
package types
func OAdd16(a uint16, b uint16) (res uint16, overflowed bool) {
	res = a + b
	overflowed = res < a
	return
}
func OAdd(a uint64, b uint64) (res uint64, overflowed bool) {
	res = a + b
	overflowed = res < a
	return
}