func IsIsogram(word string) bool {
	w := strings.ToLower(word)
	for _, letter := range w {
		if unicode.IsLetter(letter) && strings.Count(w, string(letter)) > 1 {
			return false
		}
	}
	return true
}
// IsIsogram returns whether a string is an isogram
IsIsogram returns whether a string is an isogram
// IsIsogram returns whether a string is an isogram
func IsIsogram(word string) bool {
	w := strings.ToLower(word)
	for _, letter := range w {
		if unicode.IsLetter(letter) && strings.Count(w, string(letter)) > 1 {
			return false
		}
	}
	return true
}
func IsIsogram ( word string ) bool { w := strings . ToLower ( word ) for _ , letter := range w { if unicode . IsLetter ( letter ) && strings . Count ( w , string ( letter ) ) > 1 { return false } } return true }
IsIsogram returns whether a string is an isogram
IsIsogram returns whether a string is an isogram