docs: function getAddress(loopback, family) {
    let interfaces;
    if (loopback) {
      let lo = getLoInterface();
      interfaces = lo ? [lo] : null;
    }
    interfaces = interfaces || os.networkInterfaces();
    for (let key in interfaces) {
      if (!interfaces.hasOwnProperty(key)) {
        continue;
      }
  
      for (let ipAddress of interfaces[key]) {
        if (ipAddress.family === family && ipAddress.internal === loopback) {
          return ipAddress.address;
        }
      }
    }
    return undefined;
  }