Python模块对象不可调用

Question

刚刚开始学习Python，所以我可以制作Reddit机器人并遇到麻烦。我得到的行“模块对象不可调用”：

bitcoin_price = base().get_current_price()

来自此代码：

import praw
import config
import time
import os
import requests
from exchanges import base

def bot_login():
    print("Logging in...")
    r = praw.Reddit(username = config.username,
        password = config.password,
        client_id = config.client_id,
        client_secret = config.client_secret,
        user_agent = "ZaRollaCodsta's bitcoin bot")
    print("logged in!")

    return r

def run_bot(r, comments_replied_to):

    for comment in r.subreddit('test').comments(limit=25):
        if "bitcoin" in comment.body:
            print("Found comment containing \"bitcoin\".")

            comment_reply = "Did I hear bitcoin?\nHere is the price:\n\n"

            bitcoin_price = base().get_current_price()

            comment_reply += ">" + bitcoin_price + "\n\nTo the moon!"

            comment.reply(comment_reply)

            print("Replied to comment " + comment.id)

            comments_replied_to.append(comment.id)

            with open ("comments_replied_to.txt", "a") as f:
                f.write(comment.id + "\n")

        print("Sleeping for 10 seconds...")
        #Sleep for 10 seconds...
        time.sleep(10)

def get_saved_comments():
    if not os.path.isfile("comments_replied_to.txt"):
        comments_replied_to = []
    else: 
        with open("comments_replied_to.txt", "r") as f:
            comments_replied_to = f.read()
            comments_replied_to = comments_replied_to.split("\n")

    return comments_replied_to

r = bot_login()
comments_replied_to = get_saved_comments()
while True:
    run_bot(r, comments_replied_to)

我已经尝试了Stack Overflow上的所有解决方案，但似乎都没有。