I think it's better to remove `super.`, just `traverseTreess`, in case you ever override `traverseTreess` in this class. Or, to be consistent, everywhere call `super.traverse(tree)` (the original tree that you are pattern-matching against). That would also eliminate the risk that you forget to call `traverse` on any sub-tree.

In this case, for instance, I am not sure it's correct to ignore the modifiers (the first argument in `DefDef`). Modifiers contain annotations, AFAIK. Maybe add a test that it correctly recurses in annotations (and their arguments).