PyMongo集合对象不可调用

我正在尝试创建一个Reddit刮板,它从Reddit主页中取出前100页,并将它们存储到MongoDB中。我不断收到错误:

TypeError: 'Collection' object is not callable. If you meant to call the 'insert_one' method on a 'Collection' object it is failing because no such method exists.

这是我的代码

import pymongo
import praw
import time


def main():
    fpid = os.fork()
    if fpid!=0:
        # Running as daemon now. PID is fpid
        sys.exit(0)

    user_agent = ("Python Scraper by djames v0.1")
    r = praw.Reddit(user_agent = user_agent)    #Reddit API requires user agent

    conn=pymongo.MongoClient()
    db = conn.reddit
    threads = db.threads


    while 1==1:    #Runs in an infinite loop, loop repeats every 30 seconds
        frontpage_pull = r.get_front_page(limit=100)    #get first 100 posts from reddit.com

        for posts in frontpage_pull:    #repeats for each of the 100 posts pulled
            data = {}
            data['title'] = posts.title
            data['text'] = posts.selftext
            threads.insert_one(data)
        time.sleep(30)

if __name__ == "__main__":
    main()