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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 load_model(self, config):
 """ Load the model extension module """

        for package_name in getattr(config.app, 'modules', []):
            module = __import__(package_name, fromlist=['model'])
            if hasattr(module, 'model'):
                return module.model
        return None