confused about sending the results to a completion handler

[edenhare]

HI. I am new to Swift, but not to AWS. I decided to dive right in and build a Swift version of a tool I wrote in python.
I am trying to get a list of the Route53 hosted zones. Here is what I have worked up to:

                let route53Client = try await Route53Client(region: region)
                try await route53Client.listHostedZones(
                    input: ListHostedZonesInput(marker: "", maxItems: 100),
                    processHostedZones( (ListHostedZonesOutputResponse, ListHostedZonesOutputError))
                )
            } catch {

I am working from the docs at https://awslabs.github.io/aws-sdk-swift/reference/0.x/AWSRoute53/Route53Client

the way I understand it is the routew53Client.listHostedZones takes an input and a completion handler. The completion handler I have here is processHostedZones. It doesn't do anything yet.

My confusion is getting the data from the routew53Client.listHostedZones call into the completion handler and how I define the type in the completion handler?

Maybe this is a basic question, but I don't get it from the docs or the Swift docs - I think this is called a Generic?

Thanks.