@Override
            public Object pre(Object t) {
                if ( ((GrammarAST)t).getType() == 3 ) {
                    return expandParameterizedLoop((GrammarAST)t);
                }
                return t;
            }
Find and replace
     ID*[','] with ID (',' ID)*
     ID+[','] with ID (',' ID)+
     (x {action} y)+[','] with x {action} y (',' x {action} y)+

 Parameter must be a token.
 todo: do we want?
tool/src/org/antlr/v4/tool/GrammarTransformPipeline.java