谁帮我解释下这个python调用excel的小程序，有点看不懂，谢谢

import excellib


_AD_.FehlertypenDict = {1:['DI_ET_PLAUSI','Plausibilitaet'],
2:['DI_ET_SHTGND','Kurzschluss nach Masse'],
3:['DI_ET_SHTBATT','Kurzschluss nach Ubatt'],
4:['DI_ET_WIREBREAK','Unterbrechung'],
5:['DI_ET_OVERCURRENT','Strom zu hoch'],
6:['DI_ET_OC','Open Circuit']}

ExcelAppl = None
_AD_.FehlercodesDict = {}
ExcelDataList = []

ExcelAppl = excellib.Application()

FilePath = _AD_.ExcelFilePath

try:
#open the excel file
Workbook = ExcelAppl.OpenWorkbook(FilePath)

FirstCell = 'A3'
LastCell = 'C26'
SheetIndex = 2

ExcelDataList = Workbook.GetData(FirstCell, LastCell,SheetIndex)

for i in range(0,len(ExcelDataList)):
_AD_.FehlercodesDict[int(ExcelDataList[i][0])] = [ExcelDataList[i][1], ExcelDataList[i][2]]



ExcelAppl.CloseWorkbook(FilePath)
ExcelAppl = None
Workbook = None

except:
ExcelAppl.CloseWorkbook(FilePath)
ExcelAppl = None
Workbook = None

顶一下