input: Write a function to check if a given string contains all the words in a 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.lower() not in input_string.lower():
   return False
   return True
  
  assert contains_words('This is a test', ['test', 'this', 'is'])==True
  assert contains_words('Hello world', ['world', 'hello'])==False
  assert contains_words('This is a sample text', ['sample', 'text', 'this'])==False
  assert contains_words('Python is fun', ['python', 'is', 'fun'])==True
  assert contains_words('', ['empty', 'string'])==False
output: def contains_words(input_string, words):
      for word in words:
          if word.lower() not in input_string.lower():
              return False
      return True