여러 XML 파일 병합

저는이 스크립트 ( Merge multiple XML files from command line )를 사용하여 Debian Jessie에서 xml 파일을 결합했습니다. CENTOS 6.6 x86_64를 실행하는 전용 서버로 이동하는 중입니다. 새 환경에서 스크립트가 작동하도록하는 데 문제가 있습니다. 어떤 도움을 주시면 감사하겠습니다.

파이썬 버전 2.7

스크립트

#!/usr/bin/env python
import sys
from xml.etree import ElementTree

def run(files):
    first = None
    for filename in files:
        data = ElementTree.parse(filename).getroot()
        if first is None:
            first = data
        else:
            first.extend(data)
    if first is not None:
        print ElementTree.tostring(first)

if __name__ == "__main__":
    run(sys.argv[1:])

오류

0+0 records in
0+0 records out
0 bytes (0 B) copied, 9.8139e-05 s, 0.0 kB/s
0+0 records in
0+0 records out
0 bytes (0 B) copied, 7.7816e-05 s, 0.0 kB/s
0+0 records in
0+0 records out
0 bytes (0 B) copied, 7.3015e-05 s, 0.0 kB/s
0+0 records in
0+0 records out
0 bytes (0 B) copied, 7.1727e-05 s, 0.0 kB/s
0+0 records in
0+0 records out
0 bytes (0 B) copied, 7.6014e-05 s, 0.0 kB/s
0+0 records in
0+0 records out
0 bytes (0 B) copied, 8.1163e-05 s, 0.0 kB/s
Traceback (most recent call last):
  File "/location/private/xmlcombine.py", line 17, in <module>
    run(sys.argv[1:])
  File "/location/private/xmlcombine.py", line 12, in run
    first.extend(data)
AttributeError: _ElementInterface instance has no attribute 'extend'
Traceback (most recent call last):
  File "/location/private/xmlcombine.py", line 17, in <module>
    run(sys.argv[1:])
  File "/location/private/xmlcombine.py", line 12, in run
    first.extend(data)
AttributeError: _ElementInterface instance has no attribute 'extend'
Traceback (most recent call last):
  File "/location/private/xmlcombine.py", line 17, in <module>
    run(sys.argv[1:])
  File "/location/private/xmlcombine.py", line 12, in run
    first.extend(data)
AttributeError: _ElementInterface instance has no attribute 'extend'
Process Completed