Golf code challenge

Brian — tiny code-golf challenge.

Write the smallest complete program of your own that:

accepts:  light-on
returns:  Let there be light

The catch:

We count the whole runnable thing:

runtime/interpreter + executable + your program

But it has to be code you wrote for the challenge.

So:

  • no just calling an existing CLI command
  • no shelling out to echo/grep/etc. as the solution
  • no pre-existing utility doing the actual work for you

Using a language runtime/interpreter is fine, but it counts toward the size.

The task itself is deliberately trivial.

I want to compare how small the complete runnable package can be in
Rebol / Red / Glon / whatever you choose.

Smallest complete package wins.