getting started with wrapping two stores with one

wrapperStore

var store = function(substores,options){

    return {
         query: function(query){
             var defs=[];
             var results=[]
             substores.forEach(function(sub,index){
                 defs.push(when(sub.query(query), function(resultSet){
                     results[index]=resultSet;
                 }));
             }
             return when(promise.all(defs), function(results){
                    var final=[];
                    results.forEach(r){
                        final = final.concat(r);
                    });
                    return final;
             });
         }
    }

}