code: def _parse_czeng(*paths, **kwargs):
    
    filter_path = kwargs.get("filter_path", None)
    if filter_path:
      re_block = re.compile(r"^[^-]+-b(\d+)-\d\d[tde]")
      with tf.io.gfile.GFile(filter_path) as f:
        bad_blocks = {
            blk for blk in re.search(
                r"qw{([\s\d]*)}", f.read()).groups()[0].split()
        }
      logging.info(
          "Loaded %d bad blocks to filter from CzEng v1.6 to make v1.7.",
          len(bad_blocks))
  
    for path in paths:
      for gz_path in tf.io.gfile.glob(path):
        with tf.io.gfile.GFile(gz_path, "rb") as g, gzip.GzipFile(fileobj=g) as f:
          for line in f:
            line = line.decode("utf-8")  # required for py3
            if not line.strip():
              continue
            id_, unused_score, cs, en = line.split("\t")
            if filter_path:
              block_match = re.match(re_block, id_)
              if block_match and block_match.groups()[0] in bad_blocks:
                continue
            yield {
                "cs": cs.strip(),
                "en": en.strip(),
            }
docs: Generates examples from CzEng v1.6, with optional filtering for v1.7.