input: Write a function to create a Python 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 the string contains all the words, return True, otherwise 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
  assert contains_words('This is a brilliant test', ['test', 'brilliant'])==True
  assert contains_words('This is a test', ['testing', 'this'])==False
  assert contains_words('This is a 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