Traits for serializing elements. The serializer expects the data to be xml-like (with a name, and optional children, attrs, text, comments, doctypes, and processing instructions). It uses the visitor pattern, where the serializer and the serializable objects are decoupled and implement their own traits.
serialize, telling it if we want to skip the parent.
Serializer) implement this trait.
<div class="test">is represented as
(<QualName of type class>, "test").