Returns the class that will be used by the createCard method to generate
        card widgets for records.
        
        :param      record | <orb.Table>
        
        :return     <XAbstractCardWidget>

def cardClass( self, record ):
        """
        Returns the class that will be used by the createCard method to generate
        card widgets for records.
        
        :param      record | <orb.Table>
        
        :return     <XAbstractCardWidget>
        """
        return self._cardClasses.get(type(record), self._cardClasses[None])