set designer 2013 variable = rest call get id from group name?

I trying to implement https://www.c-sharpcorner.com/article/changing-permissions-using-sharepoint-2013-workflow-with-rest-call-part-3/

 

I can get the user id from the current item created by.

 

I want instead to set the principalID to a security group id

 

 

how do i set the variable principalID to the rest call above?

 

something like set principalID to rest call?

 

Cindy