def find_feat_part(artist, albumartist):
    feat_part = None

    # Look for the album artist in the artist field. If it's not
    # present, give up.
    albumartist_split = artist.split(albumartist, 1)
    if len(albumartist_split) <= 1:
        return feat_part

    # If the last element of the split (the right-hand side of the
    # album artist) is nonempty, then it probably contains the
    # featured artist.
    elif albumartist_split[-1] != '':
        # Extract the featured artist from the right-hand side.
        _, feat_part = split_on_feat(albumartist_split[-1])

    # Otherwise, if there's nothing on the right-hand side, look for a
    # featuring artist on the left-hand side.
    else:
        lhs, rhs = split_on_feat(albumartist_split[0])
        if lhs:
            feat_part = lhs

    return feat_part
Attempt to find featured artists in the item's artist fields and
dataset/ETHPy150Open beetbox/beets/beetsplug/ftintitle.py/find_feat_part