Retorna a concatenação do resultado de callbacks chamado dentro de um loop

function getCurrentScore(callback) {
    var teamScores = "", teamsLeft = teams.length;
    for(var i=0 ; i<teams.length; i++) {
        (function(i){
            PingVoteModel.count({"votedTo": "TEAM"+(i+1)}, function( err, count) {
                teamScores += "<Team" + (i+1) + "> " + count + "\t";
                if (--teamsLeft === 0) {
                    callback(teamScores);
                }
            });
        }(i));
    }
}