package is import ( "math/big" "unicode" ) func Digit(s string) bool { for _, r := range s { if !unicode.IsDigit(r) { return false } } return true } func Lower(s string) bool { for _, r := range s { if !unicode.IsLower(r) { return false } } return true } func Upper(s string) bool { for _, r := range s { if !unicode.IsUpper(r) { return false } } return true } func Prime(i int) bool { return big.NewInt(int64(i)).ProbablyPrime(0) }