COGNOS Script to modify date ranges on a Dimension

[dredden2]

I am currently using Cognos 10.2.1.
I am looking for a way to pass a value based off of today's date through to my code below:

     OpenPy "\\path_to_my_file\filename.pyj"
     DimUpdate "DimensionName"
     DimType Date EarliestDate 20170101      
     SavePy "\\path_to_my_file\filename.pyj"

I cannot figure out IBM's language to do this. I have searched high/low on IBM's site but cannot seem to figure out an automated way to do this.

Ultimately something like this; but %let does not work:

 %let earlydate=today()-730;
     
     OpenPy "\\path_to_my_file\filename.pyj"
     DimUpdate "DimensionName"
     DimType Date EarliestDate &earlyldate 
     SavePy "\\path_to_my_file\filename.pyj"

Any ideas?