What is eager execution?
> Eager execution is an experimental interface to TensorFlow that provides an imperative programming style (à la NumPy). When you enable eager execution, TensorFlow operations execute immediately; you do not execute a pre-constructed graph with Session.run().
https://github.com/tensorflow/tensorflow/tree/r1.5/tensorflo...
It's actually pretty clear (to anyone that has used TensorFlow)
https://research.googleblog.com/2017/10/eager-execution-impe...