input: Write a function to find the most frequent word in a dictionary.
  assert find_most_frequent_word({'apple': 4, 'banana': 2, 'orange': 3}) == 'apple'
  assert find_most_frequent_word({'cat': 1, 'dog': 5, 'fish': 5}) == 'dog'
  assert find_most_frequent_word({'one': 1, 'two': 2, 'three': 1}) == 'two'
output: def find_most_frequent_word(word_dict):
      return max(word_dict, key=word_dict.get)