input: Write a python function to get the values from a dictionary for each word in a string.
  assert get_words("this is a test", {"this": "that", "is": "not", "a": "an", "test": "exam"}) == ["that", "not", "an", "exam"]
  assert get_words("hello world", {"hello": "hi", "world": "earth"}) == ["hi", "earth"]
  assert get_words("python is fun", {"python": "snake", "is": "is", "fun": "joy"}) == ["snake", "is", "joy"]
output: def get_words(s, d):
      return [d[word] for word in s.split()]