Uh alright let's try using an existing thing.
A bit more explicit.
Add the new requirement to setup.py too
Clarify a constant name now that http has more stuff in it.
Py3 Nonsense
Yes I am actually dumb enough to write my own URL class.

I don't like existing ones one bit.

Like many things here, this doesn't work. But it's a start.
Manager will change soon, but until then, avoid Python's annoying lack of frozendict by being lazy.
And now Requests have URLs.