I've recently begun playing around with Python and since I am not a "Hello, world" kind of guy I decided a good first project would be to do something I know well already and Authorize.Net's AIM API is something I know about as well as you can. Unfortunately for Python developers, although Authorize.Net offers sample code in a variety of programming languages, Python isn't one of them. Also, based on my research (i.e. a quick Google search) it seems like there may be some room for a Python module that handles the Authorize.Net AIM API as the only one I found seems to be Zope related. The module provided and explained below is standalone and does not require Zope.
Coding Library: Python

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