Add __all__ to mnist.py
Add __all__ to mnist.py

emailweixu/Paddle,livc/Paddle,pkuyym/Paddle,lispc/Paddle,lispc/Paddle,emailweixu/Paddle,lispc/Paddle,emailweixu/Paddle,gangliao/Paddle,lispc/Paddle,luotao1/Paddle,putcn/Paddle,lcy-seso/Paddle,putcn/Paddle,wen-bo-yang/Paddle,jacquesqiao/Paddle,Canpio/Paddle,gangliao/Paddle,lispc/Paddle,livc/Paddle,cxysteven/Paddle,PaddlePaddle/Paddle,gangliao/Paddle,cxysteven/Paddle,chengduoZH/Paddle,putcn/Paddle,hedaoyuan/Paddle,gangliao/Paddle,hedaoyuan/Paddle,gangliao/Paddle,wen-bo-yang/Paddle,lispc/Paddle,baidu/Paddle,yu239/Paddle,pkuyym/Paddle,luotao1/Paddle,PaddlePaddle/Paddle,Canpio/Paddle,reyoung/Paddle,yu239/Paddle,hedaoyuan/Paddle,yu239/Paddle,putcn/Paddle,yu239/Paddle,Canpio/Paddle,jacquesqiao/Paddle,pkuyym/Paddle,pengli09/Paddle,emailweixu/Paddle,chengduoZH/Paddle,livc/Paddle,QiJune/Paddle,lispc/Paddle,pengli09/Paddle,tensor-tang/Paddle,chengduoZH/Paddle,QiJune/Paddle,lispc/Paddle,cxysteven/Paddle,lcy-seso/Paddle,wen-bo-yang/Paddle,luotao1/Paddle,pengli09/Paddle,Canpio/Paddle,reyoung/Paddle,Canpio/Paddle,tensor-tang/Paddle,luotao1/Paddle,tensor-tang/Paddle,emailweixu/Paddle,wen-bo-yang/Paddle,putcn/Paddle,pkuyym/Paddle,emailweixu/Paddle,QiJune/Paddle,pengli09/Paddle,chengduoZH/Paddle,wen-bo-yang/Paddle,tensor-tang/Paddle,baidu/Paddle,lcy-seso/Paddle,tensor-tang/Paddle,hedaoyuan/Paddle,livc/Paddle,livc/Paddle,PaddlePaddle/Paddle,PaddlePaddle/Paddle,cxysteven/Paddle,jacquesqiao/Paddle,pengli09/Paddle,PaddlePaddle/Paddle,baidu/Paddle,Canpio/Paddle,Canpio/Paddle,cxysteven/Paddle,wen-bo-yang/Paddle,reyoung/Paddle,lcy-seso/Paddle,gangliao/Paddle,luotao1/Paddle,reyoung/Paddle,livc/Paddle,yu239/Paddle,gangliao/Paddle,chengduoZH/Paddle,cxysteven/Paddle,QiJune/Paddle,hedaoyuan/Paddle,putcn/Paddle,yu239/Paddle,baidu/Paddle,Canpio/Paddle,reyoung/Paddle,QiJune/Paddle,jacquesqiao/Paddle,luotao1/Paddle,reyoung/Paddle,QiJune/Paddle,hedaoyuan/Paddle,hedaoyuan/Paddle,yu239/Paddle,livc/Paddle,cxysteven/Paddle,yu239/Paddle,PaddlePaddle/Paddle,jacquesqiao/Paddle,PaddlePaddle/Paddle,wen-bo-yang/Paddle,jacquesqiao/Paddle,pkuyym/Paddle,pkuyym/Paddle,baidu/Paddle,hedaoyuan/Paddle,emailweixu/Paddle,pengli09/Paddle,lcy-seso/Paddle,luotao1/Paddle,lcy-seso/Paddle,pengli09/Paddle,pengli09/Paddle