title: 'ah' not listed when calling HTML::Mason::Request->new()
body: <p>I'm writing codes which are originally from <a href="http://modperlbook.org/html/B-18-1-Apache-Session-8212-Maintain-Session-State-Across.html" rel="nofollow">http://modperlbook.org/html/B-18-1-Apache-Session-8212-Maintain-Session-State-Across.html</a> to use session. </p>
  
  <p>But I got an error as below:
      "
      The following parameter was passed in the call to HTML::Mason::Request->new() but was   not listed in the validation options: ah\n\nStack:\n
      "</p>
  
  <p>When I looked at Request.pm, 
  'ah' is in its doc part, but not in <strong>PACKAGE</strong>->valid_params. Do I use 'my $status = $ah->handle_request($r);' wrongly?</p>
  
  <p>Oh, I'm using HTML:Mason 1.42-2, Apache2 and perl5.</p>
  
  <p>Thanks,</p>
  
  <p>Yang</p>