input: Write a function to generate a list of lists of words from a list of strings. Each inner list should contain the first word of the string followed by all following words for that string. If the input list is empty, return an empty list.
  def get_word_lists(strings):
      word_lists = []
      for string in strings:
          words = string.split(" ")
          word_list = []
          for i in range(len(words)):
              word_list.append(words[i:])
          word_lists.append(word_list)
      return word_lists
  assert get_word_lists(["Hello world", "This is a test"])==[[["Hello", "world"]], [["This", "is", "a", "test"]]]
  assert get_word_lists([])==[]
output: def get_word_lists(strings):
      word_lists = []
      for string in strings:
          words = string.split(" ")
          word_lists.append([words[0:i+1] for i in range(len(words))])
      return word_lists