code: function sequencer(map) {
          return function () {
              if (this == undefined) return "";
              var i=0;
              return String.prototype.split.apply(this, [""]).map(map).join("");
          };
      }
docs: Extends a mapper with the current index inside the string as a second argument.
  @param {function(string, number):string} map Sequencing function
  @returns {function(string):string} Wrapped sequencer
  @private