input: Write a python function to capitalize all words in a list.
  assert capitalize_words(['these', 'are', 'some', 'words']) == ['These', 'Are', 'Some', 'Words']
  assert capitalize_words(['hello', 'world']) == ['Hello', 'World']
  assert capitalize_words(['python', 'is', 'awesome']) == ['Python', 'Is', 'Awesome']
output: def capitalize_words(words):
      return [word.capitalize() for word in words]