You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: ddaniel27.go
    path of file: ./repos/retos-programacion-2023/Retos/Reto #9 - HETEROGRAMA, ISOGRAMA Y PANGRAMA [Fácil]/go
    
    the code of the file until where you have to start completion: package main

func main() {
	println(isPangram("the quick brown fox jumps over the lazy dog"))
	println(isIsogram("uncopyrightable"))
	println(isHeterogram("jumping"))
}

func isHeterogram(w
    
func isIsogram(word string) bool {
	letters := make(map[rune]int)
	for _, letter := range word {
		if letter == ' ' || letter == '-' {
			continue
		}
		letters[letter] += 1
	}
	var aux int
	for _, count := range letters {
		if aux == 0 {
			aux = count
			continue
		}
		if aux != count {
			return false
		}
	}
	return true
}