# File lib/rack/openid.rb, line 92
    def call(env)
      req = Rack::Request.new(env)
      if req.params["openid.mode"]
        complete_authentication(env)
      end

      status, headers, body = @app.call(env)

      qs = headers[AUTHENTICATE_HEADER]
      if status.to_i == 401 && qs && qs.match(AUTHENTICATE_REGEXP)
        begin_authentication(env, qs)
      else
        [status, headers, body]
      end
    end