Easy way to backup all VMs via the API, without enumerating them one by one?

Hi,

We have a test lab for users to spin up VMs on demand.

Is there an easy way to call backup on all created VMs, without needing to explicitly specify the set?

(As a hack, I assume we can enumerate the VMs using the API, and then call backup individually on each one - but I wondered if there was perhaps a cleaner way, to just do a bulk "backup all my VMs please!")

Regards,
Victor