function forEach(from, callback) {
        var _loop_1 = function (key) {
            if (hasOwnProperty.call(from, key)) {
                var result = callback({ key: key, value: from[key] }, function () {
                    delete from[key];
                });
                if (result === false) {
                    return { value: void 0 };
                }
            }
        };
        for (var key in from) {
            var state_1 = _loop_1(key);
            if (typeof state_1 === "object")
                return state_1.value;
        }
    }
Iterates over each entry in the provided set. The iterator allows
to remove elements and will stop when the callback returns {{false}}.