code: public function removeAt($index)
      {
          $this->validateIndex($index);
          $items = $this->items;
  
          $partA = array_slice($items, 0, $index);
          $partB = array_slice($items, $index + 1, count($items));
          $items = array_merge($partA, $partB);
  
          $col = new static ($this->type);
          $col->setItemsFromTrustedSource($items);
  
          return $col;
      }
docs: {@inheritdoc}