docs: function(object) {
      var output = "^(",
        units = object.unit,
        gap = object.gap,
        endReg = object.endReg,
        addon = object.addon;
      output += units.map(function(value, index) {
        if (index % 2 !== 0) {
          return;
        }
        return value + "|";
      }).join("");
      output += ")" + gap + endReg;
      return new RegExp(output);
    }