code: function(tagName) {
      tagName = tagName || get(this, 'tagName');
  
      // Explicitly check for null or undefined, as tagName
      // may be an empty string, which would evaluate to false.
      if (tagName === null || tagName === undefined) {
        tagName = 'div';
      }
  
      return Ember.RenderBuffer(tagName);
    }
docs: Creates a new renderBuffer with the passed tagName. You can override this
  method to provide further customization to the buffer if needed. Normally
  you will not need to call or override this method.
  
  @returns {Ember.RenderBuffer}