Flow equivalent of task.setNewGuid()?

[gjz]

I have a workflow that I'm converting to flow and have run into an issue with a catalog task.  

In my workflow, I create a catalog task that stays open until the end of the workflow.  At the end, I run a script to close that specific task.  In a workflow script, I set a scratchpad variable to task.setNewGuid() so I can identify which catalog task I need to close at the end of the workflow in the Run Script step.

How can I do the same in Flow Designer?  I've tried using looking up the record and separately updating the record, but neither action will allow me to use the catalog task at all, it's grayed out.

[gjz · Accepted solution]

For anyone who might need this, I figured out a way.  To me it's clunky like most of Flow, it takes several steps to do the same workflow step.  That said...

Right after creating the catalog task (which doesn't have Wait for completion checked), set a string flow variable to the catalog task.  Then I used the flow variable in a Look up record action at the end of the flow to find the specific catalog task and close it with an Update record action.  Five steps for something that took two in workflow.  At least it works.