function countUniqueWords(sentence: string): number {
  let words: string[] = sentence.toLowerCase().split(" ");
  let counter: number = 0;
  let countWord: string[] = [];

  if(sentence.trim().length == 0) return 0

  words.forEach( word => {
    if(!countWord.includes(word)) {
      counter++;
      countWord.push(word);
    }
  })

  return counter;
}

// No modificar: necesario para evaluar el resultado.
export { countUniqueWords };