input: Write a python function to check if a word is in a predefined dictionary.
  assert check_word_in_dictionary("apple")==True
  assert check_word_in_dictionary("banana")==True
  assert check_word_in_dictionary("kiwi")==False
  assert check_word_in_dictionary("grapes")==True
output: def check_word_in_dictionary(word):
      predefined_dictionary = {"apple", "banana", "grapes"}
      return word in predefined_dictionary