#!/usr/bin/perl

use strict;
use warnings;

my $head = {data => 0, prev => undef, next => undef};
my $previous = $head;

while (<DATA>){
    chomp;
    $previous->{next} = {
                "data" => $_ , 
                "next" => undef,
                "prev" => $previous,
            };
    $previous = $previous->{next};
}

my $curr = $head;
while (1) {
	last unless defined $curr->{next};
	print "Current: ", $curr->{data}, 
	      "\tPrevious: ", $curr->{prev}{data} // "", 
	      "\tNext: ", $curr->{next}{data} // "", "\n";
	$curr = $curr->{next};
}

__DATA__
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