Using computed.or incorrectly

application.controller.js

import Ember from 'ember';

const {
  computed: { or }
} = Ember;

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  thing: or('someKey', 'this is wrong') 
});

application.template.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{thing}}
<br>
<br>

twiddle.json

{
  "version": "0.6.5",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.4.3/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.4.0/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.4.3/ember-template-compiler.js"
  }
}