src/Bag.php
public function merge($list)
    {
        return $this->createFrom(array_merge($this->items, Arr::from($list)));
    }
public function merge($list)
    {
        return $this->createFrom(array_merge($this->items, Arr::from($list)));
    }
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