There are explainers linked from each of the examples - in this case https://elv.sh/learn/scripting-case-studies.html#update-servers-in-parallel.elv https://elv

There are explainers linked from each of the examples - in this case https://elv.sh/learn/scripting-case-studies.html#update-servers-in-parallel.elv https://elv.sh/learn/scripting-case-studies.html#update-serv.... Hopefully that clears up things for you!