我有以下代碼，我希望將輸入文件和輸出文件拉入到其他函數中，但是，這些代碼似乎沒有返回。仍然很新，所以如果這很簡單，請道歉。# PYTHON 3.76 ONLY# Version 0.0.1import xml.etree.cElementTree as etimport pandas as pdimport sys, getoptdef main(argv):    inputfile = ''    outputfile = ''    try:        opts, args = getopt.getopt(argv,"hi:o:",["ifile=","ofile="])    except getopt.GetoptError:        print ('test.py -i <inputfile> -o <outputfile>')        sys.exit(2)    for opt, arg in opts:        if opt == '-h':            print ('test.py -i <inputfile> -o <outputfile>')            sys.exit()        elif opt in ("-i", "--ifile"):            inputfile = arg        elif opt in ("-o", "--ofile"):            outputfile = arg    print ('Input file is "', inputfile)    print ('Output file is "', outputfile)    return inputfile, outputfileif __name__ == "__main__":    main(sys.argv[1:])# convert XML to dataframedef xml2df(xml_data):    tree = et.parse(xml_data)    print (tree.getroot())    root = tree.getroot()    print ("tag=%s, attrib=%s" % (root.tag, root.attrib))    #iterate over each value for room and each user and add to rows    rows = []    for child in root.iter('rooms'):        roomId, roomTitle = 'id', 'ttl'    for it in child:        if it.tag == 'room':            roomId = it.findtext('roomID')            roomTitle = it.findtext('roomTitle')            roomStatus = it.findtext('status')            isAnonymous = it.findtext('isAnonymous')返回錯誤回溯（最近調用最后）：文件“parse_pChatDump.py”，第 63 行，在 df = xml2df（輸入文件） 名稱錯誤：未定義名稱“輸入文件”