input: from typing import List
  
  
  def sentiment_analysis(tweets: List[str]) -> List[str]:
      """
      Classify each tweet in the input list as either 'Positive' or 'Negative'.
      >>> sentiment_analysis(['I love this movie!', 'This is terrible.'])
      ['Positive', 'Negative']
      >>> sentiment_analysis(['Great day today', 'Not happy with the service'])
      ['Positive', 'Negative']
      """
output:     positive_keywords = ['love', 'great', 'happy']
      negative_keywords = ['terrible', 'not happy']
      
      results = []
      for tweet in tweets:
          tweet_lower = tweet.lower()
          if any(keyword in tweet_lower for keyword in positive_keywords):
              results.append('Positive')
          elif any(keyword in tweet_lower for keyword in negative_keywords):
              results.append('Negative')
          else:
              results.append('Positive')  # Default to 'Positive' if no keywords match
      
      return results