From the doc

// Create a VPC for our cluster.
const vpc = new awsx.ec2.Vpc("my-vpc");
const allVpcSubnets = vpc.privateSubnetIds.concat(vpc.publicSubnetIds);

awsx.ec2.Vpc

is expecting a second args so this will not work

vpc.privateSubnetIds

is a promise and you can’t concat Promises. What is going on? Is this doc outdated?