def get_app_config(self, app_label):
        """
        Imports applications and returns an app config for the given label.

        Raises LookupError if no application exists with this label.
        """
        self.check_apps_ready()
        try:
            return self.app_configs[app_label]
        except KeyError:
            message = "No installed app with label '%s'." % app_label
            for app_config in self.get_app_configs():
                if app_config.name == app_label:
                    message += " Did you mean '%s'?" % app_config.label
                    break
            raise LookupError(message)

    # This method is performance-critical at least for Django's test suite.
dataset/ETHPy150Open django/django/django/apps/registry.py/Apps.get_app_config/original