use warnings;
use strict;
use Algorithm::Odometer::Tiny;

my $h = {a=>1, b=>2, c=>3, d=>4};

my $odo = Algorithm::Odometer::Tiny
	->new( [sort keys %$h], [sort keys %$h] );

while ( my @x = $odo->() ) {
	print "outer: $x[0], inner: $x[1]\n";
}