docs: function(target, types, up) {
  		var best = null,
  			rating = Number.MAX_VALUE;
  		this._rateall(target, types, up, function(type, rate) {
  			if (rate > -1 && rate < rating) {
  				rating = rate;
  				best = type;
  			}
  		});
  		return best;
  	}