chore: add flattenVNodes

src/composition/use-relation.ts

@@ -0,0 +1,25 @@
+import { VNode, isVNode, VNodeNormalizedChildren } from 'vue';
+
+export function flattenVNodes(children: VNodeNormalizedChildren) {
+  const result: VNode[] = [];
+
+  const traverse = (children: VNodeNormalizedChildren) => {
+    if (!Array.isArray(children)) {
+      return;
+    }
+
+    children.forEach((child) => {
+      if (isVNode(child)) {
+        result.push(child);
+
+        if (child.children) {
+          traverse(child.children);
+        }
+      }
+    });
+  };
+
+  traverse(children);
+
+  return result;
+}