title: Google colab does not find keras.engine when reinitializing a neural net weights
body: <p>I need to create a simple model of Neural net with small number of nodes, to train it and then to evaluate certain parameters in the resulting already trained network. </p>
  
  <p>I need to repeat this several times(>100). Thus, I just want to reinitialize the weights instead of creating a new model every single time.</p>
  
  <p>Here is the problematic part of my code:</p>
  
  <pre><code> import tensorflow as tf
   from tensorflow import keras
   from keras import backend as K
  
   def reinitLayers(model):
       session = K.get_session()
       for layer in model.layers: 
           if isinstance(layer,keras.engine.network.Network):
               reinitLayers(layer)
  ....
  </code></pre>
  
  <p>This is what I am getting:</p>
  
  <pre><code> "module 'tensorflow._api.v1.keras' has no attribute 'engine'"
  </code></pre>
  
  <p>However there exist keras.engine:
  <a href="https://github.com/tensorflow/tensorflow/tree/master/tensorflow/python/keras/engine" rel="nofollow noreferrer">https://github.com/tensorflow/tensorflow/tree/master/tensorflow/python/keras/engine</a></p>
  
  <p>Very similar question is this one:
  <a href="https://stackoverflow.com/questions/51186448/attributeerror-module-keras-engine-has-no-attribute-input-layer/55250831#55250831">AttributeError: module &#39;keras.engine&#39; has no attribute &#39;input_layer&#39;</a>
  However, the answer there doesn't help me.</p>
  
  <p>The same issue is described here, but the thread there does not help either:
  <a href="https://github.com/keras-team/keras/issues/341" rel="nofollow noreferrer">https://github.com/keras-team/keras/issues/341</a></p>