I'm working on this issue, but I have some questions:

1. If dump() function is only for debugging purpose, and since from dump() is where we will pass the sort_attrs keyword in False in order to conserve the order, I don't see how from dump() we can handle the order of the keyword arguments. The sorted occurs in line 926 (https://github.com/python/cpython/blob/master/Lib/xml/etree/ElementTree.py#L926) and 982(https://github.com/python/cpython/blob/master/Lib/xml/etree/ElementTree.py#L982) when xml or html are serialized. Or could we pass the sort_attrs to the functions _serialize_html/_serialize_xml and there handle this?

2. Just a comment, maybe sort_attrs is not ambiguous? For a user would be clear that sort_attrs will order the arguments in lexical order or maybe he/she could be confused and take it as that will respect the order of the keywords passed?