code: function expandOptions(val, allowValues) {
      val = val || [];
      var trail = [];
      return val.reduce(function (a, c) {
          if (!constants_1.FLAG_SHORT.test(c) || constants_1.FLAG_COUNT.test(c))
              return a.concat(c);
          var split = c.slice(1).split('').map(function (n) { return "-" + n; });
          if (allowValues)
              return a.concat(split);
          trail = trail.concat(split); // shift to end can't have values.
          return a;
      }, []).concat(trail);
  }
docs: Expands options arguments into multiple singular arguments.
  
  @example [-abc] becomes [-a, '-b', '-c']
  
  @param val the value to be expanded.
  @param allowValues when true short flag groups can have values.