Generates examples from TMX file.

def _parse_tmx(path):
  """Generates examples from TMX file."""
  def _get_tuv_lang(tuv):
    for k, v in tuv.items():
      if k.endswith("}lang"):
        return v
    raise AssertionError("Language not found in `tuv` attributes.")

  def _get_tuv_seg(tuv):
    segs = tuv.findall("seg")
    assert len(segs) == 1, "Invalid number of segments: %d" % len(segs)
    return segs[0].text

  with tf.io.gfile.GFile(path) as f:
    for _, elem in ElementTree.iterparse(f):
      if elem.tag == "tu":
        yield {
            _get_tuv_lang(tuv):
                _get_tuv_seg(tuv) for tuv in elem.iterfind("tuv")
        }
        elem.clear()