title: print hash key with converted hash xml simple
body: <p>I am new with perl and i want to get keys of Hash table generated using <code>XML::SIMPLE</code> module 
  like this</p>
  
  <pre><code>$data = $xml-&gt;XMLin("tp.xml");
  </code></pre>
  
  <p>Here is the structure generated</p>
  
  <pre><code>$VAR1 = {
        'technical-profile' =&gt; {
                               'WEB' =&gt; {
                                        'mandatory-param' =&gt; {
                                                             'value' =&gt; 'high',
                                                             'name' =&gt; 'screenCapability',
                                                             'case-sensitive' =&gt; 'no'
                                                           }
                                      },
                               'WAP/PDA' =&gt; {
                                            'description' =&gt; 'wap/sparphone',
                                            'mandatory-param' =&gt; {
                                                                 'value' =&gt; 'low|intermediate',
                                                                 'name' =&gt; 'screenCapability',
                                                                 'case-sensitive' =&gt; 'no'
                                                               }
                                          },
                               'WAP' =&gt; {
                                        'description' =&gt; 'wap/sparphone',
                                        'mandatory-param' =&gt; {
                                                             'value' =&gt; 'low',
                                                             'name' =&gt; 'screenCapability',
                                                             'case-sensitive' =&gt; 'no'
                                                           }
                                      }
                             }
      };
  </code></pre>
  
  <p>I tried this </p>
  
  <pre><code>print "Key: $_" foreach (keys%data);
  </code></pre>
  
  <p>but i get nothing; i want to print the <code>WEB</code> <code>WAP/PDA</code> and <code>WAP</code> how is that possible please ?</p>