def set_allowed_by(rack_env, allowed_by)
      Env.new(rack_env).tap do |env|
        env.allowed_by = allowed_by
      end.to_rack
    end
def set_allowed_by(rack_env, allowed_by)
      Env.new(rack_env).tap do |env|
        env.allowed_by = allowed_by
      end.to_rack
    end
Mark what authorized the request in the Rack environment

 @param [Hash] :rack_env Rack environment
 @param [String] :allowed_by what allowed this request