tr: add comments and cleanup call signature
tr: add comments and cleanup call signature

From review comments on #4649 left post-merge.

hashicorp/nomad,dvusboy/nomad,dvusboy/nomad,nak3/nomad,hashicorp/nomad,nak3/nomad,burdandrei/nomad,dvusboy/nomad,burdandrei/nomad,hashicorp/nomad,burdandrei/nomad,dvusboy/nomad,burdandrei/nomad,nak3/nomad,nak3/nomad,burdandrei/nomad,burdandrei/nomad,hashicorp/nomad,dvusboy/nomad,hashicorp/nomad,nak3/nomad,nak3/nomad,burdandrei/nomad,dvusboy/nomad,dvusboy/nomad,nak3/nomad,hashicorp/nomad