Here we define a subroutine

NOTE: It must be defined within [[! ... !] to avoid redefinition! [! sub Hello { return 'Hello world' ; } !] Now we call the subroutine: [+ Hello () +]

$XXXXXX::var = [+ defined ($XXXXXX::var)?$XXXXXX::var:'' +]
Setup some variable outside our namespace, which should not be cleaned up
[- $XXXXXX::var = 1 -] $XXXXXX::var = [+ defined ($XXXXXX::var)?$XXXXXX::var:'' +]
[! sub CLEANUP { print LOG "This will be called before variable cleanup\n" ; undef $XXXXXX::var ; } !]

Ok.