input: Write a python function to tokenize a given sentence using NLTK's word_tokenize and apply Lancaster stemming. 
  assert tokenize_and_stem("Hello, how are you?") == ['hello', ',', 'how', 'ar', 'you', '?']
  assert tokenize_and_stem("This is a test sentence.") == ['thi', 'is', 'a', 'test', 'sent']
  assert tokenize_and_stem("Stemming is fun!") == ['stem', 'is', 'fun', '!']
output: def tokenize_and_stem(sentence):
      import nltk
      from nltk.tokenize import word_tokenize
      from nltk.stem import LancasterStemmer
      
      # Ensure the necessary resources are downloaded
      nltk.download('punkt', quiet=True)
      
      # Tokenize the sentence
      tokens = word_tokenize(sentence)
      
      # Initialize LancasterStemmer
      stemmer = LancasterStemmer()
      
      # Apply stemming to each token
      stemmed_tokens = [stemmer.stem(token) for token in tokens]
      
      return stemmed_tokens