virtual_servers in get_persistence_record

The documentation I've been reading say I should be able to get the persistence records of a list of virtual servers (https://devcentral.f5.com/wiki/iControl.LocalLB__VirtualServer__get_persistence_record.ashx)

However this perl code results in an empty reference being returned:

 Get list of all virtual servers
$Persistence = &GetInterface ("$sHost", "LocalLB", "VirtualServer" ); iControl function
$soapResponse = $Persistence->get_list();
&checkResponse($soapResponse);
@vs_list = @{$soapResponse->result};

 Get persistence records of all virtual servers
$soapResponse = $Persistence->get_persistence_record(
        SOAP::Data->name( virtual_servers => [@vs_list] ),
        SOAP::Data->name( persistence_modes => ["PERSISTENCE_MODE_NONE"] )
);
&checkResponse($soapResponse);
@prsAofA = @{ $soapResponse->result };

I've tried flattening the array to be a true string only to get an error saying the string is not a valid server name. The only time get_persistence_record returns any valid data is if I send just one virtual server name.

What is the correct formatting I need to use to send a "sequence of virtual servers"?