def _converter ( self , value ) : if not isinstance ( value , datetime . date ) : raise TypeError ( '{0} is not valid date' . format ( value ) ) return value
python datetime is valid date
Convert raw input value of the field .
def _converter(self, value):
        """Convert raw input value of the field."""
        if not isinstance(value, datetime.date):
            raise TypeError('{0} is not valid date'.format(value))
        return value