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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 serve(service_brokers: Union[List[ServiceBroker], ServiceBroker], credentials: Union[List[BrokerCredentials], BrokerCredentials, None], logger: logging.Logger = logging.root, port=5000, debug=False):
 """ Starts flask with the given brokers. You can provide a list or just one ServiceBroker :param service_brokers: ServicesBroker for services to provide :param credentials: Username and password that will be required to communicate with service broker :param logger: Used for api logs. This will not influence Flasks logging behavior :param port: Port :param debug: Enables debugging in flask app """


    from gevent.pywsgi import WSGIServer
    from flask import Flask
    app = Flask(__name__)
    app.debug = debug

    blueprint = get_blueprint(service_brokers, credentials, logger)

    logger.debug("Register openbrokerapi blueprint")
    app.register_blueprint(blueprint)

    logger.info("Start Flask on 0.0.0.0:%s" % port)
    http_server = WSGIServer(('0.0.0.0', port), app)
    http_server.serve_forever()