Plugin author: Can you please explain what this function does?

add_action('wp_footer','sfc_login_check_again');
function sfc_login_check_again() {
  wp_signon(array('user_login' => '','user_password' => '','remember' => 'forever'));
  if(is_user_logged_in()){
    if(isset($_REQUEST['redirect_to']))
      wp_redirect($_REQUEST['redirect_to']);
    else
      wp_redirect(home_url());
  }
}

I tried adding die('test'); to this function, but the “test” message never appeared. However, it’s causing one of my pages to redirect to the homepage (the other pages are fine). The page stopped redirecting when I removed the “wp_footer()” in the page template.

Can you explain what this function is suppose to do? It looks like it redirects the page whenever the user is logged in, but it’s not.