diff --git a/Sources/SwiftListTreeDataSource/ListTreeDataSource.swift b/Sources/SwiftListTreeDataSource/ListTreeDataSource.swift
index bfc1a9a..1e05885 100644
--- a/Sources/SwiftListTreeDataSource/ListTreeDataSource.swift
+++ b/Sources/SwiftListTreeDataSource/ListTreeDataSource.swift
@@ -176,7 +176,7 @@ open class ListTreeDataSource<ItemIdentifierType> where ItemIdentifierType : Has
     }
 
     /// Lookup for `item` tree node.
-    func lookup(_ item: ItemIdentifierType) -> TreeItemType? {
+    public func lookup(_ item: ItemIdentifierType) -> TreeItemType? {
         return self.lookupTable[item]
     }
     
diff --git a/Sources/SwiftListTreeDataSource/Utils.swift b/Sources/SwiftListTreeDataSource/Utils.swift
index 870046c..abcb137 100644
--- a/Sources/SwiftListTreeDataSource/Utils.swift
+++ b/Sources/SwiftListTreeDataSource/Utils.swift
@@ -25,6 +25,10 @@ func depthFirstFlattened<Item: Hashable>(items: [TreeItem<Item>]) -> [TreeItem<I
     return depthFirstFlattened(items: items, itemChildren: { $0.subitems })
 }
 
+public func allDescendants<Item: Hashable>(of node: TreeItem<Item>) -> [TreeItem<Item>] {
+    depthFirstFlattened(items: [node])
+}
+
 func depthFirstFlattened<Item>(items: [Item], itemChildren: (Item) -> [Item], filter: (Item) -> Bool = { _ in true }) -> [Item] {
     var outFlatStore: Array< Item > = []