I thought (hoped!) that `mjs` was just a hack that node used to get around the fact they couldn't do native javascript modules with .js extensions nicely - but

I thought (hoped!) that `mjs` was just a hack that node used to get around the fact they couldn't do native javascript modules with .js extensions nicely - but (with --experimental-modules for now, but default eventually) the `mjs` file extension hack should be gone forever soon (I thought!).