I have a problem with my tweepy bot in pythone

i have this script for follow back in python with tweepy

followers = tweepy.Cursor(api.followers).items()

for follower in followers:

    num = random.randint(0,9)

    if num == 1:

            follower.follow()

this script follows all of my followers. But i want follow who i didnt follow back.i mean my new followers not all of my followers. what should i writ in script? for example i want plus if follower is not in my following. but i dont know what should i write. please help me