You can pass method="html"
to the tostring()
call.
Demo:
>>> import xml.etree.ElementTree as etree
>>> data = """
... <root>
... <person/>
... <person></person>
... </root>
... """
>>> tree = etree.fromstring(data)
>>> print etree.tostring(tree, method="html")
<root>
<person></person>
<person></person>
</root>