This function returns the examples in the raw (text) form.

def _generate_examples(self, data_file):
    """This function returns the examples in the raw (text) form."""
    target_language = self.builder_config.target_language

    with tf.io.gfile.GFile(data_file) as f:
      for i, line in enumerate(f):
        line_parts = line.strip().split("\t")
        if len(line_parts) != 2:
          raise ValueError(("Wrong data format in line {}. The line '{}' does "
                            "not have exactly one delimiter.").format(i, line))
        source, target = line_parts[0].strip(), line_parts[1].strip()

        yield {"en": source, target_language: target}