def _step99(self, in_row, tmp_row, out_row):
park_info = '<STR_LIT>'<EOL>for field in self._mandatory_fields:<EOL><INDENT>if field not in out_row or not out_row[field]:<EOL><INDENT>if park_info:<EOL><INDENT>park_info += '<STR_LIT:U+0020>'<EOL><DEDENT>park_info += field<EOL><DEDENT><DEDENT>return park_info, None<EOL>
Validates all mandatory fields are in the output row and are filled.

:param dict in_row: The input row.
:param dict tmp_row: Not used.
:param dict out_row: The output row.