How to use the n8n-core.UserSettings.writeUserSettings function in n8n-core

let tunnelSubdomain;
					if (process.env[TUNNEL_SUBDOMAIN_ENV] !== undefined && process.env[TUNNEL_SUBDOMAIN_ENV] !== '') {
						tunnelSubdomain = process.env[TUNNEL_SUBDOMAIN_ENV];
					} else if (userSettings.tunnelSubdomain !== undefined) {
						tunnelSubdomain = userSettings.tunnelSubdomain;
					}

					if (tunnelSubdomain === undefined) {
						// When no tunnel subdomain did exist yet create a new random one
						const availableCharacters = 'abcdefghijklmnopqrstuvwxyz0123456789';
						userSettings.tunnelSubdomain = Array.from({ length: 24 }).map(() => {
							return availableCharacters.charAt(Math.floor(Math.random() * availableCharacters.length));
						}).join('');

						await UserSettings.writeUserSettings(userSettings);
					}

					const tunnelSettings: localtunnel.TunnelConfig = {
						host: 'https://hooks.n8n.cloud',
						subdomain: tunnelSubdomain,
					};

					const port = config.get('port') as number;

					// @ts-ignore
					const webhookTunnel = await localtunnel(port, tunnelSettings);

					process.env.WEBHOOK_TUNNEL_URL = webhookTunnel.url + '/';
					this.log(`Tunnel URL: ${process.env.WEBHOOK_TUNNEL_URL}\n`);
					this.log('IMPORTANT! Do not share with anybody as it would give people access to your n8n instance!');
				}