input: Write a function to check if a given string contains all the words in a list of words. Return True if all words are found in the string, otherwise return False.
  def contains_words(input_string, words):
   for word in words:
   if word.lower() not in input_string.lower():
   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('Completely Different', ['test', 'this', 'is'])==False
  assert contains_words('', ['test', 'this', 'is'])==False
  assert contains_words('Test is this', [])==True
output: def contains_words(input_string, words):
      for word in words:
          if word.lower() not in input_string.lower():
              return False
      return True