code: func IsUTFLetter(str string) bool {
  	for _, v := range str {
  		if !unicode.IsLetter(v) {
  			return false
  		}
  	}
  	return true
  
  }
docs: //IsUTFLetter check if the string contains only unicode letter characters.
  //Similar to IsAlpha but for all languages. Empty string is valid.