keyForAttribute(attr) {
    return dasherize(attr);
  }
Used to customize the key for an attribute. By default, compound attribute names are dasherized.

    For example, the JSON:API document for a `post` model with a `commentCount` attribute would be:

    ```js
    {
      data: {
        id: 1,
        type: 'posts',
        attributes: {
          'comment-count': 28
        }
      }
    }
    ```

    @method keyForAttribute
    @param {String} attr
    @return {String}
    @public