Compile all the table cells.

        Returns a list of rows. The rows may have different lengths because of
        column spans.

def _process_table_cells(self, table):
        """ Compile all the table cells.

        Returns a list of rows. The rows may have different lengths because of
        column spans.

        """

        rows = []

        for i, tr in enumerate(table.find_all('tr')):
            row = []

            for c in tr.contents:
                cell_type = getattr(c, 'name', None)

                if cell_type not in ('td', 'th'):
                    continue

                rowspan = int(c.attrs.get('rowspan', 1))
                colspan = int(c.attrs.get('colspan', 1))
                contents = self._process_children(c).strip()

                if cell_type == 'th' and i > 0:
                    contents = self._inline('**', contents)

                row.append(Cell(cell_type, rowspan, colspan, contents))

            rows.append(row)

        return rows