input: Write a function to take in two strings as input and output a list of all the words in both strings.
  def string_to_list(s1, s2):
      s1_list = s1.split()
      s2_list = s2.split()
      output_list = s1_list + s2_list
      return output_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("Hello world", "Python programming")==['Hello', 'world', 'Python', 'programming']
  assert string_to_list("", "Test this function")==['Test', 'this', 'function']
  assert string_to_list("Single", "")==['Single']
  assert string_to_list("", "")==[]
output: def string_to_list(s1, s2):
      s1_list = s1.split()
      s2_list = s2.split()
      output_list = s1_list + s2_list
      return output_list