Excuse me, I don't understand why the bias relation are not the same with the weight relation,as below img shows. Is there something wrong? <img width="726" alt="2017-12-15 9 01 42" src="https://user-images.githubusercontent.com/7439194/34041389-4491cfa4-e1db-11e7-89bd-aae9451873d9.png">