input: Write a function that takes in a string and a list of words and returns true if the string contains all the words in the list. 
  
  def contains_words(input_string, words):
   for word in words:
   if word not in input_string:
   return False
   return True
  
  print(contains_words('This is a test', ['test', 'this', 'is'])) # True
  print(contains_words('This is a test', ['test', 'this', 'not'])) # False
  print(contains_words('Hello world', ['world', 'Hello'])) # True
  print(contains_words('Python is fun', ['fun', 'python'])) # False
  print(contains_words('', ['test'])) # False
output: def contains_words(input_string, words):
   for word in words:
   if word.lower() not in input_string.lower():
   return False
   return True