利用到normalization，requests，jsons，爬取dow指數據

# -*- coding: utf-8 -*-
import json
import re
import requests

def retrieve_dji_list():
    try:
        url = 'http://money.cnn.com/data/dow30/'
        res = requests.get(url)
    except ConnectionError as e:
        print(e)
    pattern = re.compile(
        'class="wsod_symbol">(.*?)<\/a>.*?<span.*?>(.*?)<\/span>.*?\n.*?class="wsod_stream">(.*?)<\/span>')
    dji_list_raw = re.findall(pattern, res.text)
    dji_list = []
    for item in dji_list_raw:
        dji_list.append({
            'code': item[0],
            'name': item[1],
            'price': float(item[2])
        })
    return dji_list


def retrieve_quotes_historical(stock_code, start = '', end = ''):
    quotes = []
    url = 'https://finance.yahoo.com/quote/%s/history?p=%s' % (stock_code, stock_code)
    try:
        r = requests.get(url)
    except ConnectionError as err:
        print(err)
    m = re.findall('"HistoricalPriceStore":{"prices":(.*?),"isPending"', r.text)
    if m:
        quotes = json.loads(m[0])
    quotes = quotes[::-1]
    return [item for item in quotes if not 'type' in item] 
    ```