input: Write a function to determine if a string contains all the words in a given list. If the string contains all the words, return True; otherwise, return False. If the list of words is empty, return True.
  
  def contains_words(input_string, words):
   for word in words:
   if word.lower() not in input_string.lower():
   return False
   return True
  
  print(contains_words('This is a test', ['test', 'This', 'is'])) # True
  print(contains_words('This is a test', ['test', 'not', 'found'])) # False
  print(contains_words('This is a test', [])) # True
  print(contains_words('', ['test'])) # False
  print(contains_words('This is a test', ['THIS', 'IS', 'TEST'])) # True
output: def contains_words(input_string, words):
      for word in words:
          if word.lower() not in input_string.lower():
              return False
      return True