#!/usr/bin/perl
use strict;
use warnings;
use YAML::Syck;

my $hash = {
            'k1'=>'v1',
            'k2'=>'v2',
            'k3'=>'v3',
           };
# Part 1 - works fine
while ( my ($k, $v) = each(%$hash) )
{
    print "$k, $v\n";
}

# Part 3 - use foreach loop instead of while(each)

foreach my $k (keys %$hash)
{
    print "$k, $hash->{$k}\n";
    DumpFile("test.yml", $hash);
}

__END__
stdout prints:

k3, v3
k2, v2
k1, v1
k3, v3
k2, v2
k1, v1

test.yml file has:
--- 
k1: v1
k2: v2
k3: v3