Return the format used to create the name of a variation of the current
        dynamic field. Use a default one ('fieldname_%s') if not set when the
        field was initialized

def format(self):
        """
        Return the format used to create the name of a variation of the current
        dynamic field. Use a default one ('fieldname_%s') if not set when the
        field was initialized
        """
        if self.dynamic_version_of is not None:
            return self.dynamic_version_of.format

        if not self._format:
            self._format = '%s_%%s' % self.name
        return self._format