input: Write a function to determine whether a given sentence is an 'affirmative' sentence or a 'negative' sentence. If the sentence contains any negation words, it should be classified as 'Negative'. If not, it should be classified as 'Affirmative'. Assuming the sentence provided is in English and may contain mixed case words. 
  assert isAffirmativeorNegative("He always comes late but I dont mind.") == "Negative"
  assert isAffirmativeorNegative("She is very happy today.") == "Affirmative"
  assert isAffirmativeorNegative("No one was there.") == "Negative"
  assert isAffirmativeorNegative("The weather is nice.") == "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"}
      words = sentence.lower().split()
      for word in words:
          if word in negation_words:
              return "Negative"
      return "Affirmative"