def add_ending_slash(directory: str) -> str:
    """add_ending_slash function

    Args:
        directory (str): directory that you want to add ending slash

    Returns:
        str: directory name with slash at the end

    Examples:
        >>> add_ending_slash("./data")
        "./data/"
    """
    if directory[-1] != "/":
        directory = directory + "/"
    return directory