title: Update different session by key
body: <p>Let's say I have two sessions. One has <code>$_SESSION['email'] = 'abc'</code>, the other has <code>$_SESSION['email'] = 'xyz'</code>. Both of these have <code>$_SESSION['show'] = 0</code></p>
  
  <p>While using the computer with <code>$_SESSION['email'] = abc</code>, I want to change <code>$_SESSION['show']</code> to <code>1</code> for the user with <code>$_SESSION['email'] = 'xyz'</code>. </p>
  
  <p>Basically I want to update a different user's session. Is this possible?</p>