我有这段代码，用beautifulsoup来抓取facebook，但是在'str'部分有一个错误。我读到python读这个像是一个变量，应该是一个函数。但是我还是不明白这一点。

from  selenium import webdriver
from selenium.webdriver.chrome.options import Options
from bs4 import BeautifulSoup
import time
import re
import json
import pandas as pd
from account_credentails import username, password

class Post_Scraper:
    """
    Post_Scraper class allows to scrape Facebook Posts based on search queries.
    """
    LOGIN_URL = "https://www.facebook.com"
    REACTIONS_NAMES = ['Like', 'Angry', 'Love', 'Haha', 'Sad','Care', 'Wow']

    def __init__(self, driver_path, posts_url) -> None:
        driver_path=driver_path('C:\Program Files\Python 3.9\chromedriver.exe')
        self.driver = webdriver.Chrome(driver_path=driver_path)
        self.posts_url = posts_url.replace("www", "mbasic")

    def login(self, username, password) -> None:
        """
        Login to a Facebook Account.

        Args:
            username ('str'))
                Facebook account username/email
            password ('str')
                Facebook account password    
        """
        self.driver.get(self.LOGIN_URL)
        time.sleep(2)
        email_ = self.driver.find_element_by_name("email")
        pass_ = self.driver.find_element_by_name("pass")
        email_.send_keys(username)
        time.sleep(1)
        pass_.send_keys(password)
        time.sleep(2)
        email_.submit()
        time.sleep(10)

我收到类似于"TypeError：'str'对象不可调用'，那么我应该怎么做呢？