--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/zamikongine/thing.nim	Mon Jan 09 11:04:19 2023 +0700
@@ -0,0 +1,20 @@
+{.experimental: "codeReordering".}
+
+type
+  Part* = object of RootObj
+    thing: ref Thing
+
+  Thing* = object of RootObj
+    parent*: ref Thing
+    children*: seq[ref Thing]
+    parts*: seq[ref Part]
+
+iterator partsOfType*[T: ref Part](root: ref Thing): T =
+  var queue = @[root]
+  while queue.len > 0:
+    let thing = queue.pop
+    for part in thing.parts:
+      if part of T:
+        yield T(part)
+    for child in thing.children:
+      queue.insert(child, 0)