private static void replaceTupleVariables(HashMap<String,String> varChanges,TupleExpr tuple,Map<String,Value> valMap) throws Exception {
  TupleVarRenamer visitor=new TupleVarRenamer(varChanges,valMap);
  tuple.visit(visitor);
}

private static void replaceTupleVariables ( HashMap < String , String > varChanges , TupleExpr tuple , Map < String , Value > valMap ) throws Exception { TupleVarRenamer visitor = new TupleVarRenamer ( varChanges , valMap ) ; tuple . visit ( visitor ) ; }
given a hashmap containing variable substitutions and a tuple , this method uses a visitor to iterate through the tuple and make the necessary substitutions
