#! perl -sw
use 5.010;
use strict;
use List::Util qw[ shuffle ];

our $I ||= 1e6;

sub genHash {
    my %hash;
    @hash{ shuffle 'a'..'d' } = 1 .. 4;
    return \%hash;
}

my $datum = join ' ', keys %{ genHash() };
warn $datum . "\n";

for my $i ( 1 .. $I ) {
    my $test = join ' ', keys %{ genHash() };
    die "test failed after $i iters: $datum vs. $test\n"
        unless $datum eq $test;
}

say "Test passed for $I iterations"

__END__
C:\test>junk2
c a b d
Test passed for 1000000 iterations

##</code><code>##

@hashA{ 'a'..'d' } = 1..4;;

@hashB{ 'a'..'j' } = 1 .. 10;;

delete $hashB{ $_ } for 'e' .. 'j';;

print scalar %hashA;;
4/8

print scalar %hashB;;
4/16

print join ' ', keys %hashA;;
c a b d

print join ' ', keys %hashB;;
a d c b

##</code><code>##

my $value_key = join $;, @students{ sort keys %{ $students{ $key } } };