input: Write a function to take in two strings as input and return a list of all the words in both strings. If the function is given an empty string or empty list, it should return an empty list.
  assert string_to_list("I want to make a difference", "The journey to success is long")==['I', 'want', 'to', 'make', 'a', 'difference', 'The', 'journey', 'to', 'success', 'is', 'long']
  assert string_to_list("", "The journey to success is long")==['The', 'journey', 'to', 'success', 'is', 'long']
  assert string_to_list("I want to make a difference", "")==['I', 'want', 'to', 'make', 'a', 'difference']
  assert string_to_list("", "")==[]
output: def string_to_list(str1, str2):
      if not str1 and not str2:
          return []
      words1 = str1.split() if str1 else []
      words2 = str2.split() if str2 else []
      return words1 + words2