How to use the mediafile.serialize function in mediafile

# Recompute the key if it is missing or invalid
        valid_keys = keyfinder.notations.camelot.values()

        if not media.key or not media.key.strip("0") in valid_keys:
            media.key = ""
            self.execute_paralell(self.compute_key, identifier, media)

        # Request more details from beatport
        if importer.beatport.has_metadata(media):
            self.execute_paralell(self.beatport_update, identifier, media)

        self.mediafiles[identifier] = media
        self.cache_art(media.artwork)

        # Report track details
        track = mediafile.serialize(media, trim_path=self.import_path)
        self.send_details(identifier, track)

def report_state(self, ws):
        # Report existing tracks and current processes. Events will be batched
        # together and dispatched.
        for identifier, media in self.mediafiles.items():
            track = mediafile.serialize(media, trim_path=self.import_path)
            self.send_details(identifier, track)

        for identifier, process in self.processing:
            self.send_processing(identifier, process)

# Track is a single
    if len(tracks) == 1:
        media.disc  = ''
        media.track = ''
        media.album = ''

    # Track is part of an album (multiple tracks)
    else:
        media.track.total = len(tracks)
        media.disc = '1/1'

    if media.genre in genre_remapping:
        media.genre = genre_remapping[media.genre]

    updated = mediafile.serialize(media)

    # Return only changed values
    return {k: v for k, v in updated.items() if updated[k] != orig[k]}

response = requests.get(release_url)
    release = bs4.BeautifulSoup(response.content, 'html.parser')

    # Get the list of tracks
    tracks = release.select('div.bucket.tracks ul.bucket-items li')

    # Get a mapping of track details (under the artwork)
    details = release.select('ul.interior-release-chart-content-list')[0]
    details = details.select('li')

    details = [i.find_all('span') for i in details]
    details = {s[0].text.lower(): s[1].text.strip() for s in details}

    # Update the track, reporting only modified fields.
    orig = mediafile.serialize(media)

    media.release = details['catalog']

    # Track is a single
    if len(tracks) == 1:
        media.disc  = ''
        media.track = ''
        media.album = ''

    # Track is part of an album (multiple tracks)
    else:
        media.track.total = len(tracks)
        media.disc = '1/1'

    if media.genre in genre_remapping:
        media.genre = genre_remapping[media.genre]