[Zope] File handling under Zope

Hello! I'd like to make files in the OS (Linux), under Zope. I try this, but it doesn't work. DTML method: <dtml-call expr="writeFile(this(), id='test')">
Python Script "writeFile": filename = '/tmp/' + id file = open(filename, 'w') file.write('foo, bar, text\n') file.close But I get an error: Error Type: NameError Error Value: open How should I try this? Lajos