input: Write a python function to detect sentiment of a review.
  assert detect_sentiment("I love this product! It's amazing.") == "positive"
  assert detect_sentiment("I hate this product. It's the worst.") == "negative"
  assert detect_sentiment("This product is okay, not bad but not great either.") == "neutral"
output: def detect_sentiment(review):
      positive_words = ["love", "amazing", "great", "excellent", "fantastic"]
      negative_words = ["hate", "worst", "terrible", "awful", "bad"]
      
      review_lower = review.lower()
      
      positive_count = sum(word in review_lower for word in positive_words)
      negative_count = sum(word in review_lower for word in negative_words)
      
      if positive_count > negative_count:
          return "positive"
      elif negative_count > positive_count:
          return "negative"
      else:
          return "neutral"