input: 
  from typing import List
  
  def clean_tweet(tweet: str) -> List[str]:
      """ Removes all punctuation, special characters, and stopwords from a given tweet.
      >>> clean_tweet("I'm so excited to be going to the #MuseumTour! #BigDay #travel")
      ['excited', 'going', 'MuseumTour', 'BigDay', 'travel']
      """
  
output:     import re
      from nltk.corpus import stopwords
  
      stop_words = set(stopwords.words('english'))
      words = re.findall(r'\b\w+\b', tweet)
      cleaned_words = [word for word in words if word.lower() not in stop_words]
      return cleaned_words