block-followers.py

from time import sleep
try:
    from twitter import Api
    import twitter
except:
    print('Requires python-twitter: pip install python-twitter')
    exit(1)

api = Api(
    consumer_key='...',
    consumer_secret='...',
    access_token_key='...',
    access_token_secret='...',
)

screen_name = 'SCREEN_NAME_HERE'

cursor = -1

while True:
    print(cursor)
    next_cursor, _, followers = api.GetFollowersPaged(
        cursor=cursor,
        count=100,
        screen_name=screen_name,
    )
    for user in followers:
        print('{} ({})'.format(user.name, user.screen_name))
        try:
            api.CreateBlock(user_id=user.id)
        except twitter.error.TwitterError as e:
            pass
        sleep(0.5)
    if next_cursor:
        cursor = next_cursor
    else:
        break