code: function(json) {
  	return({
  		values: json,
  		depth: 1,
  
  		// map over all rows to get the set of properties available in each document
  		series_list: _.reduce(json, function(res, row, key) {
  			return _.uniq( res.concat( _.plain( row ).keys().value() ) );
  		}, [])
  	});
  }
docs: format a collection of Rows into a json object compatible with the Google-Vis helper library.