code: function parseGroupedInterval(){
    var options = Array.prototype.slice.call(arguments);
    return function(res){
      var dataset = new Dataset()
        .type('grouped-interval');
      each(res.result, function(record, i){
        var index = options[0] && options[0] === 'timeframe.end' ? record.timeframe.end : record.timeframe.start;
        if (record.value.length) {
          each(record.value, function(group, j){
            var label;
            each(group, function(value, key){
              if (key !== 'result') {
                label = key;
              }
            });
            dataset.set([ String(group[label]), index ], group.result);
          });
        }
        else {
          dataset.appendRow(index);
        }
      });
      return dataset;
    }
  }
docs: var myParser = Dataset.parser('grouped-interval', 'timeframe.end');