input: Write a function to query Twitter to get the most recent tweets from a user using the provided Twitter API credentials. The function should take a username as input and return the text of the tweets. If no tweets are found, the function should return an empty list. If the username is empty, the function should return None.
  assert get_most_recent_tweets("@elonmusk")==['Tweet text 1', 'Tweet text 2']
  assert get_most_recent_tweets("@user_with_no_tweets")==[]
  assert get_most_recent_tweets("")==None
output: def get_most_recent_tweets(username):
      if not username:
          return None
      # Assuming the Twitter API is accessed via a library like tweepy
      # and the API credentials are already set up.
      import tweepy
      api = tweepy.API(auth)
      try:
          tweets = api.user_timeline(screen_name=username, count=2)
          return [tweet.text for tweet in tweets]
      except tweepy.TweepError:
          return []