acmol

When we build bigflow, we will use pip install readline in this file: [bigflow_python/build_python.sh](https://github.com/baidu/bigflow/blob/master/bigflow_python/build_python.sh) Sometimes it will fail. But I guess maybe it's the network problem. But we should check...

Actually, you can use: ``` def mean(p): return p.sum() / p.count() # this is a sugar for p.sum().map(lambda s, c: s / c, p.count()) ``` to implement `mean` in one...

I'm curious about this too.

如果可以，我这边后续会把我们这边相关的修改提交一个pull request