use strict;
use warnings;

use Data::Dumper;
use JSON;

my $ds = { };
# Show that $ds is an empty hashref.
print Data::Dumper->Dump( [ \$ds, ], [ qw( *ds ) ], ), qq{\n}; 

$ds->{trans2}[0] = 90;
push @{$ds->{trans2}}, 20;
# Show that element 'trans2' of $ds now points to a 2-element array.
print Data::Dumper->Dump( [ \$ds, ], [ qw( *ds ) ], ), qq{\n}; 

# Loop through the structure and print all elements.
foreach my $k ( sort { $a cmp $b } keys %{$ds} ) {
    print qq{\t}, $k, qq{\t=>\n};
    foreach my $i ( 0 .. $#{$ds->{$k}} ) {
        print qq{\t} x 2, qq{[$i]\t=>\t}, $ds->{$k}[$i], qq{\n};
    }
}

# Encode in JSON format for transmission
my $eson = encode_json( $ds );
print $eson, qq{\n};

# Decode from JSON format, for verification
my $nson = decode_json( $eson );
print Data::Dumper->Dump( [ \$nson, ], [ qw( *nson ) ] ), qq{\n};