code: func (as *availabilitySet) EnsureBackendPoolDeleted(service *v1.Service, backendPoolID, vmSetName string, backendAddressPools *[]network.BackendAddressPool) error {
  	// Do nothing for availability set.
  	return nil
  }
docs: // EnsureBackendPoolDeleted ensures the loadBalancer backendAddressPools deleted from the specified nodes.