input: Write a function to remove all punctuation, special characters and stopwords from a given tweet. Return the cleaned list of words.
  assert clean_tweet("I'm so excited to be going to the #MuseumTour! #BigDay #travel")==['excited', 'going', 'MuseumTour', 'BigDay', 'travel']
  assert clean_tweet("The quick brown fox jumps over the lazy dog.")==['quick', 'brown', 'fox', 'jumps', 'lazy', 'dog']
  assert clean_tweet("")==[]
  assert clean_tweet("!!!")==[]
  assert clean_tweet("Hello, world!")==['Hello', 'world']
output: def clean_tweet(tweet):
      import string
      from nltk.corpus import stopwords
      stop_words = set(stopwords.words('english'))
      words = tweet.split()
      cleaned_words = [word.strip(string.punctuation).lower() for word in words if word.strip(string.punctuation).lower() not in stop_words]
      return cleaned_words