common.go
func randomSelect(a []int) int {
	var tmpIndex int
	length := len(a)
	randBytes := make([]byte, length)
	if _, err := rand.Read(randBytes); err == nil {
		tmpIndex = int(randBytes[0]) % length
	}
	return a[tmpIndex]
}
func randomSelect(a []int) int {
	var tmpIndex int
	length := len(a)
	randBytes := make([]byte, length)
	if _, err := rand.Read(randBytes); err == nil {
		tmpIndex = int(randBytes[0]) % length
	}
	return a[tmpIndex]
}
// random select will return a random selection from an int slice