input: Write a python function to extract unique words from a given text.
  assert extract_unique_words("hello world and hello universe") == ["hello", "world", "and", "universe"]
  assert extract_unique_words("this is a test test") == ["this", "is", "a", "test"]
  assert extract_unique_words("repeat repeat repeat") == ["repeat"]
output: def extract_unique_words(text):
      words = text.split()
      unique_words = list(dict.fromkeys(words))
      return unique_words