gistfile1.js

 __patchItemsProperty: function (excludeIds) {
                    if (!ko.isObservable(excludeIds)) {
                        throw new Error('Expected exclude ids to be observable array');
                    };

                    var self = this,
                        oldItems = {}; // in this hash will be stored all files, key-> file.Id(), value -> file

                    self.__fillHashFromItems(oldItems, self.items());
                    self.__filterItems(excludeIds(), oldItems);
                    excludeIds.subscribe(function (newIds) {
                        self.__filterItems(newIds, oldItems);
                    });
                    
                    // NOTE (EM): please don't kick me for next code
                    // this code make subscribe on "items" update and rebuild hash with all files
                    // after this on first items notification has will be rebuilded
                    // to avoid recursion previous subscribtion will diposed and hash rebuild re-subscribe
                    var subscription = self.__subscribeHashToItemsUpdate(oldItems, function() {
                        subscription.dispose();
                        self.__filterItems(excludeIds(), oldItems);
                        self.__subscribeHashToItemsUpdate(oldItems, _.identity);
                    });
                },
                
                __subscribeHashToItemsUpdate: function(oldItems, externalHandle) {
                    var self = this;
                    return self.items.subscribe(function (newItems) {
                        self.__fillHashFromItems(oldItems, newItems);
                        externalHandle.call(self, newItems);
                    });
                },
                
                __fillHashFromItems: function (hash, items) {
                    _.each(items, function (item) {
                        hash[item.Id()] = item;
                    });
                },
                
                __filterItems: function (idsToExclude, oldItems) {
                    var filteredItems = _.chain(oldItems)
                        .filter(function (file, key) { return !_.contains(idsToExclude, key); })
                        .map(function (file) { return file; })
                        .value();

                    this.items(filteredItems);
                }