There is nothing in this commit except for the changes made by
nix-shell -p nixfmt-rfc-style --run "nixfmt ."
If this has mucked up your open branches then sorry about that. You
can probably nixfmt them to match before merging
this is a bit of an experiment to reduce the copy-paste in
examples by turning them into "application" modules.
planning to follow up with another module for "wifi router"
