Return the ID3 tag in FILENAME as a raw byte string.

def get_raw_tag_data(filename):
    "Return the ID3 tag in FILENAME as a raw byte string."
    with open(filename, "rb") as file:
        try:
            (cls, offset, length) = stagger.tags.detect_tag(file)
        except stagger.NoTagError:
            return bytes()
        file.seek(offset)
        return file.read(length)