input: Write a function to check if a given sentence is an 'affirmative' sentence or a 'negative' sentence. The function should return "Affirmative" if there are no negation words in the sentence, otherwise it should return "Negative". If the sentence is empty, it should return "Affirmative".
  
  assert isAffirmativeorNegative("He always comes late but I dont mind.")=="Negative"
  assert isAffirmativeorNegative("She is happy and content.")=="Affirmative"
  assert isAffirmativeorNegative("")=="Affirmative"
  assert isAffirmativeorNegative("No one went to the party.")=="Negative"
  assert isAffirmativeorNegative("It is not raining today.")=="Negative"
output: def isAffirmativeorNegative(sentence):
      negation_words = {"no", "not", "never", "none", "nobody", "nothing", "neither", "nor"}
      if not sentence:
          return "Affirmative"
      for word in sentence.split():
          if word.lower() in negation_words:
              return "Negative"
      return "Affirmative"