Nice article, Andy.
I assume that you will be adding some parameters to your 'variables and parameters' package in a later article?
Building variable expressions which use the values of parameters passed in from SSISDB environments is something I do all the time, and a useful technique, so I hope you will be covering that too.
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.