def dict_to_listed_dict_1d(dict_in):
    """Convert dict to listed dict where each value is a list containing one element.

    Args:
        dict_in (dict): input dict

    Returns:
        (dict): listed dict

    """
    assert isinstance(dict_in, dict)
    dict_out = dict_in
    for key, value in dict_out.items():
        dict_out.update({key: [value]})
    return dict_out