code: function cacheFor(obj, key) {
        var meta = obj['__ember_meta__'];
        var cache = meta && meta.cache;
        var ret = cache && cache[key];
  
        if (ret === UNDEFINED) { return undefined; }
        return ret;
      }
docs: Returns the cached value for a property, if one exists.
  This can be useful for peeking at the value of a computed
  property that is generated lazily, without accidentally causing
  it to be created.
  
  @method cacheFor
  @for Ember
  @param {Object} obj the object whose property you want to check
  @param {String} key the name of the property whose cached value you want
  to return
  @return {Object} the cached value