如何在 excel 中使用 Python3 时间戳？

import xlrd
import xlwt
import datetime
 
#读取收货日期，计算库龄，找到最长库龄
wb = xlrd.open_workbook('库存报表20200520.xlsx')
sheet1 = wb.sheet_by_name('Sheet1')
 
#计算当前时间，转换成excel时间戳，excel时间戳其实时间1990年1月1日
date_start = datetime.datetime(1899, 12, 31)
date_now = datetime.datetime.now()
tod = date_now - date_start
 
#计算库龄，写入数列deltas
deltas = []
titlesrow = 1
nrows = sheet1.nrows-2
for i in range(nrows):
    d = sheet1.cell(1+i, 22)
    d = int(d.value)
    delta = tod.days - d
    deltas.append(delta)
 
# 新建一个表格，记录分析结果
wb = xlwt.Workbook()
sheet = wb.add_sheet('关键数据')
 
titles = ['最长库龄', '零件号', '零件名称', '数量']
for i in range(len(titles)):
    sheet.write(0, i, titles[i])
 
# 找到库龄，写到表格
max = max(deltas)
sheet.write(1, 0, max)
 
# 库龄对应的零件号，数量
max_index = deltas.index(max)
max_part = sheet1.cell(max_index + 1, 3).value
max_name = sheet1.cell(max_index + 1, 4).value
max_num = sheet1.cell(max_index + 1, 5).value
sheet.write(1, 1, max_part)
sheet.write(1, 2, max_name)
sheet.write(1, 3, max_num)
wb.save('库存分析.xls')