def METHOD_NAME(tagwrite):
    all_paths = tagwrite.content + ["third"]
    with Tag(tagwrite.path, read_only=False) as tag:
        tag.write(all_paths)
    with Tag(tagwrite.path, read_only=True) as tag:
        read_paths = tag.read()
    assert len(set(read_paths)) == len(read_paths), "Append created duplicates"
    assert sorted(read_paths) == sorted(all_paths), "Append wrote wrong content"