How to print or use substitution variables in Groovy for ASO cube

Summary:

I had a requirement where I need to extract data from ASO cube montly, I created Sub Var in ASO cube for period and year trying to call those in groovy but script throws an error, even I tried to just print the SUb Var it didn't work

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Code Snippet (add any code snippets that support your topic, if applicable):

Cube cube = operation.application.getCube("PLNLR")
def stryear= operation.application.getSubstituionVariableValue("ActYr")
println stryear