code: function isEnabled(feature) {
      var featureValue = FEATURES[feature];
  
      if (featureValue === true || featureValue === false || featureValue === undefined) {
        return featureValue;
      } else if (_emberEnvironment.ENV.ENABLE_OPTIONAL_FEATURES) {
        return true;
      } else {
        return false;
      }
    }
docs: Determine whether the specified `feature` is enabled. Used by Ember's
  build tools to exclude experimental features from beta/stable builds.
  
  You can define the following configuration options:
  
  `EmberENV.ENABLE_OPTIONAL_FEATURES` - enable any features that have not been explicitly
  enabled/disabled.
  
  @method isEnabled
  @param {String} feature The feature to check
  @return {Boolean}
  @for Ember.FEATURES
  @since 1.1.0
  @public