code: public function merge($list)
      {
          return $this->createFrom(array_merge($this->items, Arr::from($list)));
      }
docs: Returns a bag with the items merged with the given list.
  
  Note: This should only be used for lists (zero indexed and sequential items).
  For associative arrays, use {@see replace} instead.
  
  @param iterable $list The list of items to merge
  
  @return static