def _pydantic_model_metaclass_marker_callback(self, ctx: ClassDefContext) -> None:
        """Reset dataclass_transform_spec attribute of ModelMetaclass.

        Let the plugin handle it. This behavior can be disabled
        if 'debug_dataclass_transform' is set to True', for testing purposes.
        """
        if self.plugin_config.debug_dataclass_transform:
            return
        info_metaclass = ctx.cls.info.declared_metaclass
        assert info_metaclass, "callback not passed from 'get_metaclass_hook'"
        if getattr(info_metaclass.type, 'dataclass_transform_spec', None):
            info_metaclass.type.dataclass_transform_spec = None  # type: ignore[attr-defined]
Reset dataclass_transform_spec attribute of ModelMetaclass.

        Let the plugin handle it. This behavior can be disabled
        if 'debug_dataclass_transform' is set to True', for testing purposes.
        
pydantic/v1/mypy.py