Germán Larraín

@BruceSherwood perhaps what's needed is `deepcopy` ``` python import copy ... E2 = copy.deepcopy(E1) ... ```

I see. Didn't know the underlying object was a Boost one. Without knowing specifics about this code I would say this is an objects references error. The method `visual_common.py_renderable.__copy__` doesn't...

I'm afraid right now I don't have the time to dig into VPython's internals to understand what's going on. It, almost certainly, would require a refactor, which is always dangerous...

For the record, the PR in question has been accepted thus it's now correct to install the dev version this way: `pip install git+git://github.com/BruceSherwood/vpython-wx.git`

> Is the function defusedxml.lxml.fromstring() they only part of defusedxml.lxml that we use? Yes. However, since that uses lxml, the XML-related classes that we reference all over the place in...

Useful stuff: - https://github.com/XML-Security/signxml/blob/master/signxml/util/__init__.py - https://github.com/XML-Security/signxml/blob/83c05fbfdc9efbea0ddc13cd490b423bb772ef5d/signxml/__init__.py#L185-L245

@yaselc please update PR regarding the referenced documentation

Also, please update the PR description and all the commits messages so we have stable references (SII's hosted static files can not be trusted)

Also, since this PR involves a critical part of validation, please run it against many many many real cases (you will need to code something for that I suppose). I'd...

LGTM. @jtrh your call.