Add untrack()

src/untrack.luau

@@ -0,0 +1,16 @@
+if not game then script = require "test/relative-string" end
+
+local graph = require(script.Parent.graph)
+type Node<T> = graph.Node<T>
+local refs = graph.refs
+
+local function untrack<T>(source: () -> T): T
+    local initial = #refs
+    local value = source()
+    for i = initial, #refs do
+        refs[i] = nil
+    end
+    return value
+end
+
+return untrack