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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 setup_config(form_class, config_model=None):
 """ Register the provided form as config form for the provided config model This can be used as a decorator by adding a `model` attribute to the config form:: @setup_config class ExampleConfigForm(AppDataForm):
 model = ExampleConfig :param form_class: Form class derived from AppDataForm :param config_model: Model class derived from AppHookConfig :return: """

    # allow use as a decorator
    if config_model is None:
        return setup_config(form_class, form_class.model)

    app_registry.register('config', AppDataContainer.from_form(form_class), config_model)