docs: function invertArrayOfDicts(array, opt_dictGetter, opt_this) {
      opt_this = opt_this || this;
      var result = {};
      for (var i = 0; i < array.length; i++) {
        var item = array[i];
        if (item === undefined)
          continue;
        var dict = opt_dictGetter ? opt_dictGetter.call(opt_this, item) : item;
        if (dict === undefined)
          continue;
        for (var key in dict) {
          var valueList = result[key];
          if (valueList === undefined)
            result[key] = valueList = new Array(array.length);
          valueList[i] = dict[key];
        }
      }
      return result;
    }