def unique_items_in_order(x) -> list:
    """
    Return de-duplicated list of items in order they are in supplied array.

    :param x: vector to inspect
    :return: list
    """
    ret = []
    if x is not None:
        seen = set()
        for item in x:
            if item not in seen:
                ret.append(item)
                seen.add(item)
    return ret