def METHOD_NAME(self, dlc_songs: bool, streamer_mode_active: bool,
                            diff_lower: int, diff_higher: int) -> List[str]:
    """Gets a list of all songs that match the filter settings. Difficulty thresholds are inclusive."""
    filtered_list = []
    for songKey, songData in self.song_items.items():
        if not dlc_songs and not songData.song_is_free:
            continue
        if streamer_mode_active and not songData.streamer_mode:
            continue
        if songData.easy is not None and diff_lower <= songData.easy <= diff_higher:
            filtered_list.append(songKey)
            continue
        if songData.hard is not None and diff_lower <= songData.hard <= diff_higher:
            filtered_list.append(songKey)
            continue
        if songData.master is not None and diff_lower <= songData.master <= diff_higher:
            filtered_list.append(songKey)
            continue
    return filtered_list