alphabet.go
func (a *alphabet) Index(t string) (int64, error) {
	for i, char := range a.chars {
		if char == t {
			return int64(i), nil
		}
	}
	return 0, fmt.Errorf("Element '%v' is not part of the alphabet", t)
}
func (a *alphabet) Index(t string) (int64, error) {
	for i, char := range a.chars {
		if char == t {
			return int64(i), nil
		}
	}
	return 0, fmt.Errorf("Element '%v' is not part of the alphabet", t)
}
// Index returns the index of the first instance of t in the alphabet, or an error if t is not present.