#! /usr/bin/perl
use strict;
use DB_File;

tie my %hash, 'DB_File', undef, O_CREAT|O_RDWR, 0666, $DB_BTREE;

%hash = (
  '1' => 'cat',
  '3' => 'mouse',
  '5' => 'whale'
);

tied(%hash)->seq(my $key = 2, my $ans, R_CURSOR);
print "Found key $key, answer $ans\n";