Question with guess helpers

question.ts

export const QuestionModel = types
  .model("Question")
  .props({
    id: types.identifier,
    category: types.maybe(types.string),
    type: types.enumeration(["multiple", "boolean"]),
    difficulty: types.enumeration(["easy", "medium", "hard"]),
    question: types.maybe(types.string),
    correctAnswer: types.maybe(types.string),
    incorrectAnswers: types.optional(types.array(types.string), []),
    guess: types.maybe(types.string),
  })
  .views(self => ({
    get allAnswers() {
      return shuffle(self.incorrectAnswers.concat([self.correctAnswer]))
    },
    get isCorrect() {
      return self.guess === self.correctAnswer
    },
  }))
  .actions(self => ({
    setGuess(guess: string) {
      self.guess = guess
    },
  }))