input: Write a function to determine if a given sentence is an 'affirmative' sentence or a 'negative' sentence. The function should return "Affirmative" if the sentence contains no negation words, otherwise it should return "Negative". If the input sentence is empty, it should return "Affirmative".
  
  assert isAffirmativeorNegative("He always comes late but I dont mind.") == "Negative"
  assert isAffirmativeorNegative("She is always on time.") == "Affirmative"
  assert isAffirmativeorNegative("No one can stop him.") == "Negative"
  assert isAffirmativeorNegative("") == "Affirmative"
output: def isAffirmativeorNegative(sentence):
      negation_words = {"no", "not", "never", "none", "nobody", "nothing", "neither", "nowhere", "hardly", "scarcely", "barely", "dont", "doesnt", "didnt", "wont", "wouldnt", "cant", "couldnt", "shouldnt", "isnt", "arent", "wasnt", "werent"}
      if not sentence:
          return "Affirmative"
      for word in sentence.split():
          if word.lower() in negation_words:
              return "Negative"
      return "Affirmative"