How to add next and previous in a quiz [python]

I've got the following code that converts a list into a multiple choice quiz:

def practise_test(test):
    score = 0
    for question in test:
        while True:
            print(question[question])
            reaction = input (question[options] + '\n')
            if reaction == question[answer]:
                print ('\nright answered!')
                print('The answer is indeed {}. {}\n'.format(question[answer], question[explanation]))
                score += 1
                break      
            else:
                print ('\nIncorrect answer.')
                print ('The correct answer is {}. {}\n'.format(question[answer], question[explanation]))
                break
    print (score)

But now I have to add some code to the practise_test function so that when you type: 'previous' you go to the previous question. Anyone have an idea to fix this?