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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 not_found(entity_id=None, message='Entity not found'):
 """ Build a response to indicate that the requested entity was not found. :param string message: An optional message, defaults to 'Entity not found' :param string entity_id: An option ID of the entity requested and which was not found :return: A flask Response object, can be used as a return type from service methods """

        resp = jsonify({'message': message, 'entity_id': entity_id})
        resp.status_code = 404
        return resp