[Twisted-Python] copy domish element

[Jack Bates]

i have a domish element - when i try the following,

>>> message = element
>>> del message['from']
>>> element['from']

- i get a key error

to avoid this key error, i think i want to copy the element, so i can
drop the 'from' attribute from one copy without affecting the other?

but i didn't find anything to make a copy in the domish element api

how should i avoid this key error?