Iterate through every group/host pair but won't work with 'groups'

[bur...@scalefastr.io]

I don't think Ansible will work with this scenario.

I want to iterate through every ansible role and host as a flat index.

Right now the groups variable is what I'm focused on.  Which is:

group0: 

  - host0

  - host1

group1: 

  - host2

  - host3

I want to process it as:

group0, host0

group0, host1

group1, host2

group1, host3

... but I don't think this is possible.  Is there a 'flatten' I can use?  

with_dict and with_subelements won't work.

with_subelements complains that it expects a map with a key to iterate from.