如何把这段函数调取的实时汇率变成浮点数用来运算

import requests
from lxml import etree
 
headers = {
    "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.89 Safari/537.36"
}
url = "https://www.huilv.cc/USD_CNY/"
 
 
def Get_huilv(url, headers1):
    res = requests.get(url=url, headers=headers1, timeout=2)
    #print(res.status_code)#打印状态码
    html = etree.HTML(res.text)
    USD_VS_RMB_0 = html.xpath('//div[@id="main"]/div[1]/div[2]/span[1]/text()')
    print(USD_VS_RMB_0)
    for a in USD_VS_RMB_0:
        b = a
    USD_VS_RMB_1 = float(b)
    #print(USD_VS_RMB_1)
    #print("实时汇率为：{}".format(USD_VS_RMB_1))
Get_huilv(url, headers)

比如我要用这个汇率乘以3，怎么取上面的汇率数值相乘？

import requests
from lxml import etree
headers = {
    "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.89 Safari/537.36"
}
url = "https://www.huilv.cc/USD_CNY/"

def Get_huilv(url, headers1):
    res = requests.get(url=url, headers=headers1, timeout=2)
    #print(res.status_code)#打印状态码
    html = etree.HTML(res.text)
    USD_VS_RMB_0 = html.xpath('//div[@id="main"]/div[1]/div[2]/span[1]/text()')
    print(USD_VS_RMB_0)
    for a in USD_VS_RMB_0:
        b = a
    USD_VS_RMB_1 = float(b) * 3
    print(USD_VS_RMB_1)
    print("实时汇率为：{}".format(USD_VS_RMB_1))
Get_huilv(url, headers)
'''--result
['6.3564']
19.0692
实时汇率为：19.0692
'''