minor cleanup

src/lib.rs

@@ -415,7 +415,7 @@ fn generate_serde(ident: &Ident, ty: &Type, checked_new: bool) -> TokenStream2 {
 
 fn generate_tree_key<'a>(
     ident: &Ident,
-    keys: impl Iterator<Item = &'a &'a str> + ExactSizeIterator + Clone,
+    keys: impl ExactSizeIterator<Item = &'a &'a str> + Clone,
 ) -> TokenStream2 {
     let keys = once(&"value").chain(keys);
     let num_keys = keys