input: Write a python function to analyze the sentiment of a sentence using NLTK's VADER.
  assert analyze_sentiment('The flight was really terrible.')==False
  assert analyze_sentiment('I absolutely loved the new movie!')==True
  assert analyze_sentiment('It was an average day.')==True
output: def analyze_sentiment(sentence):
      from nltk.sentiment.vader import SentimentIntensityAnalyzer
      import nltk
      nltk.download('vader_lexicon')
      
      sid = SentimentIntensityAnalyzer()
      sentiment_score = sid.polarity_scores(sentence)
      return sentiment_score['compound'] >= 0.05