input: Write a function to combine the words from two input strings into a single list. The function should split each string into individual words and then concatenate the two resulting lists. If either string is empty, the function should still return the words from the non-empty string.
  
  Input:
  String 1: "I want to make a difference"
  String 2: "The journey to success is long"
  
  Output:
  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("", "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(s1, s2):
      s1_list = s1.split()
      s2_list = s2.split()
      output_list = s1_list + s2_list
      return output_list