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The ISG is contained in a single Python module almaqa2isg which is part of the analysis_scripts.tar package which also contains the "analysisUtils" which you will also need since the ISG uses a few of their functions.
See the Analysis Utilities CASA Guide for details on how to install the package.
The first ISG alpha version was 1.7 . Described here is version 1.24 (You you can query the version using the method isg.version() ).
Usage
With your sys.path set up to import the analysisUtils, type
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