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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 allow_migrate(self, db, model):
 """ Make sure the auth app only appears in the 'duashttp' database. """

        if db == DUAS_DB_ROUTE_PREFIX:
            return model._meta.app_label == 'duashttp'
        elif model._meta.app_label == 'duashttp':
            return False
        return None