transient demo

scratch.el

(defun echo-function (&optional args)
  (interactive
   (list (transient-args 'test-transient-command)))
  (message "echo %s" args))

(define-infix-argument test-transient:--message ()
  :description "Message"
  :class 'transient-option
  :shortarg "-m"
  :argument "--message=")

(define-transient-command test-transient-command ()
  "Test transient comment."
  ["Arguments"
   (test-transient:--message)
   ("-s" "Squash" "--squash")]
  ["Actions"
   ("e" "Echo function" echo-function)])

(test-transient-command)