What's the standard import order?

So far, i've tried to keep the following order everywhere:

import <something>
...
<space>
from <something> import <fn>
...
<space>
import swh.<something>
import .<something>
...
<space>

from swh.<something> import <fn>
...
<space>
<space>
<code starts here>

In this diff, for example, i saw one inconsistency (client.py$12).

In D414#8039, @ardumont wrote:

What's the standard import order?

The import order that I try to use, and is consistent with what PEP8 advises to use is:

• imports from the Python standard library
• imports from third party modules
• (if there's a lot of them) imports from the currently used "primary" third-party module (mostly used in Django context)
• imports from other Software Heritage modules
• imports from the current module

In each of these blocks, imports are sorted by module name, irrespective of whether we import the whole module or a single name, so that we can minimize diff conflicts.