input: 
  def analyze_sentiment(text: str) -> str:
      """Analyze the sentiment of the given text and categorize it into positive, negative, or neutral.
      >>> analyze_sentiment("I love this product! It's the best I've ever used.")
      'positive'
      >>> analyze_sentiment("I hate this product. It's the worst thing I have ever bought.")
      'negative'
      >>> analyze_sentiment("The product is okay. It serves its purpose.")
      'neutral'
      """
  
output:     positive_words = ["love", "best", "great", "excellent", "awesome"]
      negative_words = ["hate", "worst", "terrible", "awful", "disappointing"]
      
      text = text.lower()
      words = text.split()
      
      positive_count = sum(word in positive_words for word in words)
      negative_count = sum(word in negative_words for word in words)
      
      if positive_count > negative_count:
          return 'positive'
      elif negative_count > positive_count:
          return 'negative'
      else:
          return 'neutral'