title: Isset not equals on multiple variables
body: <p>I have a problem using the following code.</p>
  
  <pre><code>$test1 = "test1";
  $test2 = "test2";
  
  if (!isset($test1) || (!isset($test2))) {
  
  echo "Neither exists";
  
  } else {
  
  echo "One or both exist";
  
  }
  </code></pre>
  
  <p>It works if both exists or none exists but fails if one of the variables exists.</p>
  
  <p>Searched the net but can't find a working solution.</p>
  
  <p>Thanks,</p>
  
  <p>John</p>