def call(env)
      if env['REQUEST_METHOD'] == 'GET' && env['PATH_INFO'] == logout_path(env)
        ::Rack::Response.new { |r| r.redirect(cas_logout_url(env)) }.finish
      else
        @app.call(env)
      end
    end
def call(env)
      if env['REQUEST_METHOD'] == 'GET' && env['PATH_INFO'] == logout_path(env)
        ::Rack::Response.new { |r| r.redirect(cas_logout_url(env)) }.finish
      else
        @app.call(env)
      end
    end
@param app a Rack app
 @param [String] cas_logout_url the CAS logout URL

 Rack entry point.

 Given a `GET` to the configured logout path, redirects to
 {#cas_logout_url}.  All other requests are passed through.

 @see http://www.jasig.org/cas/protocol
      Section 2.3 of the CAS 2 protocol