theme.inc

      function mergeAttributes($array) {
            $mergedAttributes = array();
            foreach(func_get_args() as $argument) {
                  foreach($argument as $key => $value) {
                        if (!isset($mergedAttributes[$key]) {
                              $mergedAttributes[$key] = array();
                        }
                        if (is_array($value)) {
                              foreach($value as $innerValue) {
                                    $mergedAttributes[$key][] = $innerValue;
                              }
                              
                        } else {
                              $mergedAttributes[$key][] = $value;
                        }
                  }
            }
            
            return $mergedAttributes;
      }


      $variables['attributes']['class'] = 'test-attribute-merge-1';
      $variables['content_attributes']['class'] ='test-content_attributes-merge-2';

      $variables['attributes']['role'] = 'attributes-role';
      $variables['content_attributes']['role'] = 'content_attributes-role';

      $variables['title_attributes']['role'] = 'title-attributes-role';
      $variables['item_attributes']['0']['role'] = 'item-attributes-role';

      //wtf why u not merge 
      $variables['attributes_test'] = mergeAttributes($variables['attributes'], $variables['content_attributes'], $variables['title_attributes']);