so i made a start on the sanitizer api...
https://wicg.github.io/sanitizer-api/#sanitizer-algorithms
which lead to the creation of DocumentFragment.
DocumentFragment is now available. it can decorate other elements that don't have a document to make available a few methods of the Document class. when you call str on it, it only returns the content.
also quite a big change to tag.
element.attributes wasn't returning due to tag sharing the name. so tag is now changed to __attributes__ which stringifies the kwargs and elements attributes prop now works. however be aware it returns not a dict but a list of Attr. I considered attributes_ to return kwargs but will see how this pans out. I was surprised all tests still passing so hope it doesn't affect anyone.
added a page for the utils to the docs. will see if they appear.