system: You are an expert security code reviewer. You will be shown a source code file. Your task is to name the single function or class that contains the specified CWE vulnerability.

OUTPUT FORMAT: Respond with the exact function or class name (no parentheses, no qualifiers, no module prefixes), wrapped in \boxed{...}. Example: `\boxed{salted_hmac}`. Output the boxed name ONLY -- no explanation, no other text.

user: ```python
# @Time : 2020/7/15
# @Author : 江海彬
# @File : spider.py


import re
import time
import twint
import pymysql


# 爬虫主体
def spider(keyword, tweets):
    # 启动配置
    c = twint.Config()
    c.Search = keyword
    c.Limit = Limit
    c.Count = True

    # 过滤含连接的tweet
    # c.Links = "exclude"

    # 只爬取热门tweet
    # c.Popular_tweets = True

    # 过滤转发
    c.Filter_retweets = True

    # 统一翻译为英语，不然后面分词时鱼龙混杂
    c.Lang = "en"

    # 爬取时间段
    c.Since = Since
    c.Until = Until
    # c.Year = "2020"

    # 开启存储
    c.Store_object = True
    c.Store_object_tweets_list = tweets

    # 隐藏控制台输出
    c.Hide_output = True

    # 代理
    # c.Proxy_host = '127.0.0.1'
    # c.Proxy_port = 7890
    # c.Proxy_type = "socks5"

    # 运行
    twint.run.Search(c)


# # 保存数据库
# def insert_db(sql, value):
#     conn = pymysql.connect(**config)

#     try:
#         with conn.cursor() as cursor:
#             cursor.executemany(sql, value)
#             conn.commit()
#             print("插入数据库成功")
#     except Exception as e:
#         print("插入数据库失败 {}".format(e))
#         conn.rollback()
#     finally:
#         conn.close()


# # 将爬虫和保存数据库操作封装
# def crawl_in_db(keyword):
#     # 爬取结果
#     tweets = []

#     # 开始爬取
#     spider(keyword, tweets)

#     # 保存到数据库
#     sql = "INSERT INTO `twitter` (`date`, `tweet`) VALUES (%s, %s)"
#     values = []

#     for tweet in tweets:
#         values.append((tweet.datestamp, tweet.tweet))

#     # for i in range(0, len(values), 1000):
#     #     insert_db(sql, values[i:i+1000])
#     #     time.sleep(4)
#     insert_db(sql, values)

#     print(keyword + "爬取完毕")

#     # 加入延时
#     time.sleep(2)


# 将爬虫和保存文件操作封装
def crawl_in_file(keyword):
    # 爬取结果
    tweets = []

    # 开始爬取
    spider(keyword, tweets)

    # 文件输出路径
    output = './data/{}.txt'.format(keyword)

    # 写入文件
    with open(output, 'wb') as f:
        for tweet_item in tweets:
            # 过滤，为分词做好准备
            # print(tweet_item.tweet)
            # 将含有&; # @ $ https的字符串、和较短(1-2位)的字符串删除，
            # 删除后会导致头尾空格合在一起，形成多余空格 |\b\w{1,2}\b
            first_filter = re.sub(r'\&\w*;|#\w*|@\w*|\$\w*|https?:\/\/.*\/*\w*|pic.twitter.com\/*\w*',
                                  '', tweet_item.tweet)
            # 将回车和换行替换为空格
            # (如果替换为空可能导致两个单词连在一起，但替换为空格则有可能产生多余空格)
            second_filter = re.sub(r'\n+|\r+|\t+', ' ', first_filter)

            # 去掉多余空格
            third_filter = re.sub(r'\s\s+', ' ', second_filter)

            emoji_pattern = re.compile(u'[\U00010000-\U0010ffff]')


            tweet = emoji_pattern.sub('', third_filter) + '\n'

            print(tweet)
            f.write(tweet.encode('UTF-8'))

    print(keyword + "爬取完毕")

    # 加入延时
    time.sleep(2)


if __name__ == '__main__':
    # ####################全局变量#################### #
    # 数据库配置
    # config = {
    #     'host': 'localhost',
    #     'user': 'root',
    #     'password': 'root',
    #     'port': 3306,
    #     'database': 'com_jiang',
    #     'charset': 'utf8mb4'
    # }

    # 爬取时间段
    Since = "2020-01-01 00:00:00"
    Until = "2020-12-30 23:59:59"

    # 要限制爬取条数，防止内存压力过大
    Limit = 10000
    # ############################################### #

    # 关键词序列
    keywords = ["Li Ziqi"]

    for keyword in keywords:
        crawl_in_file(keyword.lower())

```

Name the function or class in this code that contains a `CWE-20: Improper Input Validation` vulnerability.
Answer: crawl_in_file