help plz

#! /usr/bin/env python3.5
import pymongo
from datetime import datetime


client = pymongo.MongoClient()
db = client.db_words
collection = db.collection_words


if start[0] == 'learn':
    show_word = collection.find().limit(5)
    for i in show_word:
        try:
            while True:
                print(i["eng"])
                answer = input()
                if answer == i["ru"]:
                    i["count"] = int(i["count"]) + 1 #как сохранить изменения в i["count"] ?
                    collection.save(i["count"])