### Keras fails after upgrade

Since this might be helpful to others, I finally chased down the source of this error. There’s an incompatibility between the lambda-stack versions of tensorflow and Keras, but tensorflow includes its own keras module which can be used instead. So I changed all my imports that originally looked like this:

```python
from keras.models import Sequential
```

to this:

```python
from tensorflow.keras.models import Sequential
```