lib/rack-cas/session_store/mongoid.rb
def delete_session(env, sid, options)
      Session.where(_id: sid).delete

      options[:drop] ? nil : generate_sid
    end
def delete_session(env, sid, options)
      Session.where(_id: sid).delete

      options[:drop] ? nil : generate_sid
    end
Rack 2.0 method