问如何在python中编辑Xml文件后将其保存到pptx文件？

EN

with open('filename.xml','r') as f:
     a = f.read()
     f.closed
if 'value' in a:
     a = a.replace('value', 'newvalue')
print('success')
if 'newvalue' in a:
     print('done')
with open(filename.xml','w') as file:
     print('this works')
     file.write(a)
     print('this worked')