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. If any word in the list is not found in the string, the function should return false.
  
  def contains_words(input_string, words):
   for word in words:
   if word not in input_string:
   return False
   return True
  
  assert contains_words('This is a test', ['test', 'this', 'is']) == True
  assert contains_words('This is a test', ['test', 'this', 'not']) == False
output: def contains_words(input_string, words):
   for word in words:
   if word not in input_string:
   return False
   return True