def ordered_los_id_4(df):
    """Ordered line-of-sight id 4

    Helper predicate for sample validation

    Parameters
    ----------
    df : pandas.DataFrame
        DataFrame containing the measurements for this window

    Returns
    -------
    bool
        True if the los_ids of `df` exactly 0, 1, 2, and 3 in order
    """
    return df.los_id.tolist() == [0, 1, 2, 3]
