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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 create(self, max_wait=300, allocated_storage=None, encryption_at_rest=None, restore_to_time=None, **kwargs):
 """ Create an instance of the PostgreSQL service with the typical starting settings. :param max_wait: service is created asynchronously, so will only wait this number of seconds before giving up. :param allocated_storage: int for GBs to be allocated for storage :param encryption_at_rest: boolean for encrypting data that is stored :param restore_to_time: UTC date within recovery period for db backup to be used when initiating """


        # MAINT: Add these if there is demand for it and validated

        if allocated_storage or encryption_at_rest or restore_to_time:
            raise NotImplementedError()

        # Will need to wait for the service to be provisioned before can add
        # service keys and get env details.

        self.service.create(async=True, create_keys=False)
        while self._create_in_progress() and max_wait > 0:
            if max_wait % 5 == 0:
                logging.warning('Can take {}s for create to finish.'.format(max_wait))
            time.sleep(1)
            max_wait -= 1

        # Now get the service env (via service keys)
        cfg = self.service._get_service_config()
        self.service.settings.save(cfg)

        hostname = predix.config.get_env_key(self.use_class, 'hostname')
        os.environ[hostname] = self.service.settings.data['hostname']

        password = predix.config.get_env_key(self.use_class, 'password')
        os.environ[password] = self.service.settings.data['password']

        port = predix.config.get_env_key(self.use_class, 'port')
        os.environ[port] = str(self.service.settings.data['port'])

        username = predix.config.get_env_key(self.use_class, 'username')
        os.environ[username] = self.service.settings.data['username']

        uri = predix.config.get_env_key(self.use_class, 'uri')
        os.environ[uri] = self.service.settings.data['uri']