title: How do I get a hash slice from a hash of hashes?
body: <p>I have a hash like so:</p>
  
  <pre><code>my %h = ( a =&gt; { one =&gt; 1,
                   two =&gt; 2
               },
            b =&gt; { three =&gt; 3,
                   four =&gt; 4
               },
            c =&gt; { five =&gt; 5,
                   six =&gt; 6
               }
        );
  
  print join(',', @{$h{a}{qw/one two/}});
  </code></pre>
  
  <p>The error I get is:
  Can't use an undefined value as an ARRAY reference at q.pl line 17 
  which is the line with the print.</p>
  
  <p>What I expected is 
  1,2</p>