input: Write a function to analyze the sentiment of given text and categorize it into positive, negative, and neutral sentiments. If there are more negative sentiments than positive, return 'negative'; if there are more positive sentiments than negative, return 'positive'; otherwise, return 'neutral'. If the input text is empty, return 'neutral'.
  
  assert analyze_sentiment("I love this product!")=="positive"
  assert analyze_sentiment("This product is terrible.")=="negative"
  assert analyze_sentiment("I am neutral about this.")=="neutral"
  assert analyze_sentiment("")=="neutral"
output: def analyze_sentiment(text):
      if not text:
          return 'neutral'
      
      positive_words = ['love', 'good', 'great', 'excellent', 'positive']
      negative_words = ['hate', 'bad', 'terrible', 'awful', 'negative']
      
      positive_count = sum(text.count(word) for word in positive_words)
      negative_count = sum(text.count(word) for word in negative_words)
      
      if positive_count > negative_count:
          return 'positive'
      elif negative_count > positive_count:
          return 'negative'
      else:
          return 'neutral'