python修改excel数据保留原有样式怎么实现？

import openpyxl 

wb = openpyxl.load_workbook(u'test.xlsx') 

sheetnames =wb.sheetnames 

sheet = wb[sheetnames[0]] 

sheet['A2']='啦啦啦' 

sheet['A3']='aaa'

sheet['C2']='就废了的减肥了设计费' 

wb.save('test_result.xlsx')