title: Reference found where even-sized list expected
body: <p>I am writing this code in perl where i create a unique key and then assign a value to it. </p>
  
  <pre><code>  sub populate {
        my $file = shift;
        my %HoH = shift;
  
        open(INFILE,$file);
        .
        .
        .  
        $final_name = $prepend.$five;
        $HoH{$final_name} = $seven;
   }
  </code></pre>
  
  <p>Now i am passing in two parameters to a subroutine which id like </p>
  
  <pre><code>&amp;populate(\%abc,$file_1);
  &amp;populate(\%xyz,$file_2);
  </code></pre>
  
  <p>Why does it give me an error like this:</p>
  
  <pre><code>Reference found where even-sized list expected
  </code></pre>