Try to convert a given value to a utils.Date() instance

def _parse_date(self, dt, fmt=None):
        """ Try to convert a given value to a utils.Date() instance """
        try:
            # test if it's not a datelike instance ...
            _dt = utils.Date(dt, fmt=fmt)
        except ValueError:
            # nope, not a datelike instance
            _dt = None
        return _dt