using command line arguments #903

Using command line arguments has been great so far and I intend to use them always, but I'm not sure how to do the thing I want to do now.
I want to run a command like tmuxinator start rdev user 127.0.0.1
and have a config for rdev like this:

# .config/tmuxinator/rdev.yml

name: rdev-<%= @args[1] %>
root: ~/

# Controls whether the tmux session should be attached to automatically. Defaults to true.
attach: true

windows:
  - server: ssh <%= @args[0] %>@<%= @args[1] %>

But the arguments don't get put into the command, or the config just doesn't know what to do with them.
Is there a correct way of doing this?