'Standard grading for multiple-choice problems.
100% credit if choices are correct; 0% otherwise
Arguments: student_answers
Returns: a CorrectMap'

def grade_without_partial_credit(self, **kwargs):

    student_answers = kwargs['student_answers']
    if ((self.answer_id in student_answers) and (student_answers[self.answer_id] in self.correct_choices)):
        return CorrectMap(self.answer_id, correctness='correct')
    else:
        return CorrectMap(self.answer_id, 'incorrect')
