How to use ${un.GetParent} ?

I need to remove parent directory of installation directory if it's empty. After searching the forum i foundthis code.

${un.GetParent} $INSTDIR $R0
RMdir $R0

I've found out, that I need to include FilfeFunc.nsh.

But the error message didn't changed:
"Invalid command: ${un.GetParent}
Error in script "MC_Client_Install_client.template" on line 183 -- aborting crea
tion process"

How to call it in the correct form?

You also need to declare you're going to use GetParent by insert the un.GetParent macro after including FileFunc.nsh.

thank you, kichik 😉