title: $ and % operator being used in conjunction
body: <p>I'm busy learning Perl at the moment and I've been given some code to look at and "solve".</p>
  
  <pre><code>foreach $field (keys %$exam)
  </code></pre>
  
  <p>The code above is the area Im having difficulty in understanding. I thought $ was scalar and % was a hash and so I'm unsure what %$ is.</p>
  
  <p>Any help appreciated!</p>
  
  <p>Thanks guys.</p>