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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _register(self, form_class, check_middleware=True):
 """ Register a config form into the registry :param object form_class: The form class to register.\ Must be an instance of :py:class:`djconfig.forms.ConfigForm` :param bool check_middleware: Check\ :py:class:`djconfig.middleware.DjConfigMiddleware`\ is registered into ``settings.MIDDLEWARE_CLASSES``. Default True """

        if not issubclass(form_class, _ConfigFormBase):
            raise ValueError(
                "The form does not inherit from `forms.ConfigForm`")

        self._registry.add(form_class)

        if check_middleware:
            _check_backend()