max-niu

Results 2 issues of max-niu

## ❓ Questions and Help Hi~ I want to train the model on CPU, but how to implement the sigmoid_focalloss?

``` from __future__ import absolute_import from __future__ import division from __future__ import print_function import paddle from paddle import ParamAttr import paddle.nn as nn import paddle.nn.functional as F from paddle.vision.ops import...