def _find_header_flat(self):
        """
        Find header elements in a table, if possible. This case handles
        situations where '<th>' elements are not within a row('<tr>')
        """
        nodes = self._node.contents.filter_tags(
                    matches=ftag('th'), recursive=False)
        if not nodes:
            return
        self._log('found header outside rows (%d <th> elements)' % len(nodes))
        return nodes
Find header elements in a table, if possible. This case handles
        situations where '<th>' elements are not within a row('<tr>')