[python-bugzilla] How to attach file ?

Hello everybody, I am working on bugzilla xml-rpc by using "Bugzilla XMLRPC access module" https://pypi.python.org/pypi/python-bugzilla

How I can attach/download file of bugzilla ? According to guideline (link given below) get_attachments_by_bug($bug_id) retrieves and returns the attachments. http://www.bugzilla.org/docs/4.2/en/html/api/Bugzilla/Attachment.html

But this function didn't worked for me, I got following error message. <type 'exceptions.AttributeError'>: 'Bugzilla4' object has no attribute 'get_attachments_by_bug'