Python3时间戳如何在excel中运用？

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')