input: Write a python function to determine the sentiment of a given text based on predefined lists of positive and negative words.
  assert determine_sentiment("This is an exciting opportunity that I am looking forward to") == "positive"
  assert determine_sentiment("This is a terrible and disappointing event") == "negative"
  assert determine_sentiment("This is an event") == "neutral"
output: def determine_sentiment(text):
      positive_words = {"exciting", "looking forward", "happy", "joy", "love", "excellent", "good"}
      negative_words = {"terrible", "disappointing", "bad", "sad", "angry", "horrible", "poor"}
  
      text_words = set(text.lower().split())
      positive_count = len(text_words & positive_words)
      negative_count = len(text_words & negative_words)
  
      if positive_count > negative_count:
          return "positive"
      elif negative_count > positive_count:
          return "negative"
      else:
          return "neutral"