#!/usr/bin/perl -w
 use strict;

 my @keys = qw(one two three);
 my %hash = ( four => 4, five => 5, six => 6);
 print "@keys\n";
 if (@hash{@keys}) {
   print "yep\n";
 } else {
   print "nope\n";
 }

 push @keys, 'four';

 print "@keys\n";
 if (@hash{@keys}) {
   print "yep\n";
 } else {
   print "nope\n";
 }

 @keys = qw(one two three);
 unshift @keys,'four';
 print "@keys\n";
 if (@hash{@keys}) {
   print "yep\n";
 } else {
   print "nope\n";
 }