@staticmethod
    def validate(rows):
        valid_rows = []
        for row in rows:
            for item in row:
                if item is not None and not isinstance(item, Constrainable):
                    msg = 'Grid items must be Constrainable or None. '
                    msg += 'Got %r instead.'
                    raise TypeError(msg % item)
            valid_rows.append(tuple(row))
        return tuple(valid_rows)
See :meth:`I18n.parse_datetime`.
dataset/ETHPy150Open nucleic/enaml/enaml/layout/grid_helper.py/GridHelper.validate--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/lib/webapp2-2.3/webapp2_extras/i18n.py/parse_datetime