handles => {
   param => 'param',
},

##</code><code>##

handles => {
   param => sub {
      my $plack_request = shift->plack_request;
      return $pack_request->param(@_);
   },
},

##</code><code>##

handles => {
   param => sub {
      my $plack_request = shift->plack_request;
      return (wantarray
         ? $plack_request->param(@_)
         : $plack_request->param(@_) // ''
      );
   },
},