test tree foreach

spike/review/reinvent/ezmded/server/tree.go

@@ -26,7 +26,7 @@ func (branch Branch) forEach(preid ID, foo func(ID, Leaf) error) error {
 		return err
 	}
 	for id, child := range branch.Branches {
-		if err := child.forEach(preid.Push(string(id)), foo); err != nil {
+		if err := child.forEach(id, foo); err != nil {
 			return err
 		}
 	}