:'<,'> w outfile.hbs visual block, and then hit w for write and then the place i want it to go, like outfile.hbs
:'<,'> ! python -mjson.tool
:'<,'>s/change/tothis/g
'<,'> represents the selected text
! says run a shell command
and the python module json.tool can be run like that
it takes stdin and prints formatted json as stdout
the stdout then replaces the selected text
kind of like the sort command too
:!sort