python 3.x-存储和清除变量

目标：

使用yfinance模块刮取Yahoo Finance的代码，并创建标签，说明自上次检查以来股市是上涨还是下跌。

显然，我需要刮两次，然后得到一个值来与另一个值进行比较。我大致知道如何获取值，marketprice vs marketpriceatnextcheck，但之后如何清除这些值time.sleep? 我是否将所有内容都放在while循环中？

代码：

import time
import tkinter
from tkinter import *

IXIC = yf.Ticker("^IXIC")

root = Tk()


Text1 = str("The Nasdaq Composite is UP at last check.")
Text2 = str("The Nasdaq Composite is UP at last check.")

V1 = #marketatfirstscrape

V2 = #marketatsecondscrape


def UpDown(self):
    if V1 > V2:
        #I have this printing to terminal just to check if it works
        print(Text1)
    else:      
        print(Text2)


L1 = Label(root, text=UpDown)
L2 = Label(root, text="Have your circumstances changed?", font='times')
L1.grid(row=0, column=0, sticky=W, pady=2)
L2.grid(row=1, column=0, sticky=W, pady=2)

root.mainloop()


while True:
    tickers = ['^IXIC']
    for ticker in tickers:
            ticker_yahoo = yf.Ticker(ticker)
            data = ticker_yahoo.history()
            last_quote = data['Close'].iloc[-1]
            print(last_quote)
            time.sleep(900)