input: Write a python function to find the longest words in a dictionary where keys are words and values are their lengths.
  assert longest_words({'apple': 5, 'banana': 6, 'kiwi': 4, 'blueberry': 9}) == ['blueberry']
  assert longest_words({'a': 1, 'ab': 2, 'abc': 3, 'abcd': 4, 'abcde': 5}) == ['abcde']
  assert longest_words({'cat': 3, 'dog': 3, 'fish': 4, 'elephant': 8, 'bird': 4}) == ['elephant']
output: def longest_words(words_dict):
      max_length = max(words_dict.values())
      return [word for word, length in words_dict.items() if length == max_length]