code: function(featureId) {
          var id = Number(featureId.split("_").pop()) + 1; // zero for no feature
          if (id >= 16777216) {
              this.hitOverflow = id - 16777215;
              id = id % 16777216 + 1;
          }
          var hex = "000000" + id.toString(16);
          var len = hex.length;
          hex = "#" + hex.substring(len-6, len);
          return hex;
      }
docs: Method: featureIdToHex
  Convert a feature ID string into an RGB hex string.
  
  Parameters:
  featureId - {String} Feature id
  
  Returns:
  {String} RGB hex string.