Remove old snapshots but filter by name

Hi. I'd like to use the built in workflow 'Remove Old Snapshots' except I'd like it to filter out snapshots that have a specific phrase in the snapshot name E.G do-not-delete

I thought it would be just a case of editing the scriptable task 'Get snapshots' and changing the line

to something like

but for the life of me I can't seem to determine the name attribute and the API reference isn't clear either.

Can anyone point me in the right direction?

Thanks