Get the episode number.

    The episode number is unique for an anime and episode type, but not
    across episode types for the same anime.

def get_episode_number(episode: Episode) -> int:
    """Get the episode number.

    The episode number is unique for an anime and episode type, but not
    across episode types for the same anime.
    """
    match = _NUMBER_SUFFIX.search(episode.epno)
    return int(match.group(1))