input: Write a function to determine if a given sentence is an 'affirmative' sentence or a 'negative' sentence. If the sentence contains negation words, return 'Negative'; otherwise, return 'Affirmative'. If the sentence is empty, return 'Affirmative'.
  assert isAffirmativeorNegative("He always comes late but I don't mind.")== "Negative"
  assert isAffirmativeorNegative("She is very happy today.")== "Affirmative"
  assert isAffirmativeorNegative("They have never been to Paris.")== "Negative"
  assert isAffirmativeorNegative("We will go tomorrow.")== "Affirmative"
  assert isAffirmativeorNegative("")== "Affirmative"
output: def isAffirmativeorNegative(sentence):
      negation_words = {"not", "never", "no", "don't", "doesn't", "didn't", "can't", "won't", "isn't", "aren't"}
      if not sentence:
          return "Affirmative"
      for word in sentence.split():
          if word.lower() in negation_words:
              return "Negative"
      return "Affirmative"