code: function arrToString(arr) {
      if (arr.length === 0) return '';
      var str = '(' + Z.toString(arr[0]);
      for (var idx = 1; idx < arr.length; idx += 1) {
        str = str + ', ' + Z.toString(arr[idx]);
      }
      return str + ')';
    }
docs: optimised version of `arr.map(toString).join(', ')`