How to use the unidiff.constants.LINE_TYPE_EMPTY function in unidiff

def _append_trailing_empty_line(self):
        if not self:
            raise UnidiffParseError('Unexpected trailing newline character')
        last_hunk = self[-1]
        last_hunk.append(Line('\n', line_type=LINE_TYPE_EMPTY))

expected_source_end = source_line_no + hunk.source_length
        expected_target_end = target_line_no + hunk.target_length

        for diff_line_no, line in diff:
            if encoding is not None:
                line = line.decode(encoding)

            valid_line = RE_HUNK_BODY_LINE.match(line)
            if not valid_line:
                valid_line = RE_HUNK_EMPTY_BODY_LINE.match(line)

            if not valid_line:
                raise UnidiffParseError('Hunk diff line expected: %s' % line)

            line_type = valid_line.group('line_type')
            if line_type == LINE_TYPE_EMPTY:
                line_type = LINE_TYPE_CONTEXT
            value = valid_line.group('value')
            original_line = Line(value, line_type=line_type)
            if line_type == LINE_TYPE_ADDED:
                original_line.target_line_no = target_line_no
                target_line_no += 1
            elif line_type == LINE_TYPE_REMOVED:
                original_line.source_line_no = source_line_no
                source_line_no += 1
            elif line_type == LINE_TYPE_CONTEXT:
                original_line.target_line_no = target_line_no
                target_line_no += 1
                original_line.source_line_no = source_line_no
                source_line_no += 1
            elif line_type == LINE_TYPE_NO_NEWLINE:
                pass