.here — say which frame is being read, and go nowhere.

It asks one question and takes nothing to answer it. Reading an argument and moving somewhere would be the command doing what its name does not say, so an argument is a usage error.

import { sayWhichFrame } from './frames.ts';

import type { ReplContext } from './command.ts';

// Defined, not invoked: it reads a stopped page.
function example(repl: ReplContext) {
  return sayWhichFrame(repl, ''); // where you are, having gone nowhere
}