input: Write a function to test if a word exists in a dictionary.
  assert wordExists({"hello": "greeting", "car": "vehicle"}, "hello") == True
  assert wordExists({"hello": "greeting", "car": "vehicle"}, "bike") == False
  assert wordExists({"apple": "fruit", "banana": "fruit"}, "banana") == True
output: def wordExists(dictionary, word):
      return word in dictionary