code: @Override
  	public T visitParamsGroup(ParamsGroupContext ctx) {
  //		on(ctx);
  		appendAst(ctx, tok(PARAM_GROUP));
  		return super.visitParamsGroup(ctx);
  	}
docs: paramsGroup	: 	BEGIN_ANON_EXPR! pSeq ( ALTERNATIVE! pSeq )* END_ANON_EXPR!;