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 is considered 'negative'; otherwise, it is considered 'affirmative'. If the given sentence is empty, it should return 'Affirmative'.
  
  def isAffirmativeorNegative(sentence):
      import re 
      import nltk
      nltk.download('stopwords')
      from nltk.corpus import stopwords 
  
      def findNegation(sentence):
          negationwords = {'not', 'never', 'no', 'none', 'non', 'neither',
                           'nobody', 'nowhere', 'cannot', 'couldnt', 'shouldnt', 
                           'wouldnt', 'dont', 'didnt', 'hasnt', 'havent', 'isnt', 'arent'} 
          words = nltk.word_tokenize(sentence)
          neg = []
          for word in words:
              if word in negationwords:
                  neg.append(word)
          return neg
  
      negationwords = findNegation(sentence)
      if len(negationwords)==0: 
          return "Affirmative" 
      else: 
          return "Negative"    
  
  assert isAffirmativeorNegative("He always comes late but I dont mind.") == "Negative"
  assert isAffirmativeorNegative("I love to travel.") == "Affirmative"
  assert isAffirmativeorNegative("She is never late.") == "Negative"
  assert isAffirmativeorNegative("They have no idea.") == "Negative"
  assert isAffirmativeorNegative("") == "Affirmative"
output: def isAffirmativeorNegative(sentence):
      import re 
      import nltk
      nltk.download('stopwords')
      from nltk.corpus import stopwords 
  
      def findNegation(sentence):
          negationwords = {'not', 'never', 'no', 'none', 'non', 'neither',
                           'nobody', 'nowhere', 'cannot', 'couldnt', 'shouldnt', 
                           'wouldnt', 'dont', 'didnt', 'hasnt', 'havent', 'isnt', 'arent'} 
          words = nltk.word_tokenize(sentence)
          neg = []
          for word in words:
              if word in negationwords:
                  neg.append(word)
          return neg
  
      negationwords = findNegation(sentence)
      if len(negationwords)==0: 
          return "Affirmative" 
      else: 
          return "Negative"