input: Write a function to generate a list of lists of words from a given list of strings. Each inner list should contain the first word of each string followed by the subsequent words of that string. If the given list of strings is empty, return an empty list.
  assert get_word_lists(["Hello world", "This is a test"])==[["Hello", "world"], ["This", "is", "a", "test"]]
  assert get_word_lists(["Single"])==[["Single"]]
  assert get_word_lists([])==[]
output: def get_word_lists(strings):
      if not strings:
          return []
      result = []
      for s in strings:
          words = s.split()
          result.append(words)
      return result