my @systems = qw(
    this_system_should_be_first
    system1
    system2
    system3
    the_final_system
);
my %systems = (
    this_system_should_be_first => 'hostname_to_first_system',
    system1                     => 'hostname_to_system1',
    system2                     => 'hostname_to_system2',
    system3                     => 'hostname_to_system3',
    the_final_system            => 'hostname_to_final_system',
);