Trying to parse the result from a client.TypeOperationAsync<HealthcareService>()

[Steve Borman]

I am using the NHS FHIR eRS API and can get a successful result from this:

var result = await client.TypeOperationAsync<STU3.Model.HealthcareService>("ers.searchHealthcareServicesForPatient", parameters);

However, result is of type "Resource".  How do I convert this into a list of HealthcareService?

Thanks in advance

Steve