input: Write a python function to detect sentiment of a sentence using nltk SentimentIntensityAnalyzer.
  assert detect_sentiment("I love this product!") > 0
  assert detect_sentiment("This is the worst experience ever.") < 0
  assert detect_sentiment("It was an okay movie.") == 0
output: def detect_sentiment(sentence):
      from nltk.sentiment import SentimentIntensityAnalyzer
      sia = SentimentIntensityAnalyzer()
      sentiment = sia.polarity_scores(sentence)
      return sentiment['compound']