c:\@Work\Perl\monks>perl -Mstrict -le
"my @services = qw(BANG one two three STOP four five six);
 ;;
 my $side_effect = 'xxx';
 $side_effect =~ /xxx/ if @ARGV;
 ;;
 func('STOP');
 ;;
 func();
 ;;
 sub func {
   my $done = shift;
   while (my $serv = pop @services) {
     printf qq{$serv  };
     last if $serv =~ /$done/i
     }
   print '';
   }
"
six  five  four  STOP
three

##</code><code>##

c:\@Work\Perl\monks>perl -Mstrict -le
"my @services = qw(BANG one two three STOP four five six);
 ;;
 my $side_effect = 'xxx';
 $side_effect =~ /xxx/ if @ARGV;
 ;;
 func('STOP');
 ;;
 func();
 ;;
 sub func {
   my $done = shift;
   while (my $serv = pop @services) {
     printf qq{$serv  };
     last if $serv =~ /$done/i
     }
   print '';
   }
"  ARGUMENT
six  five  four  STOP
three  two  one  BANG