Function _reduce

deps/async.js:44–52

(arr, iterator, memo)

    };

    var _reduce = function (arr, iterator, memo) {
        if (arr.reduce) {
            return arr.reduce(iterator, memo);
        }
        _forEach(arr, function (x, i, a) {
            memo = iterator(memo, x, i, a);
        });
        return memo;
    };

    var _keys = function (obj) {
        if (Object.keys) {