What is get_lr() meaning in the optimizer.py
I use a Model based on BertModel, and when I use the BertAdam the learning rate isn't changed. And when I use `get_lr()`, the return result is `[0]`. And I see the length of state isn't 0, but why I get that?
You can use it to get the current learning rate of the `BertAdam` optimizer (which vary according to the schedules discussed in #195).