title: module 'keras.engine' has no attribute 'Layer'
body: <p>I tried to run <a href="https://github.com/matterport/Mask_RCNN" rel="nofollow noreferrer">matterport/MaskRCNN</a> code but faced the following error</p>
  <pre><code>----&gt; 6 from mrcnn.model import MaskRCNN
  
  /usr/local/lib/python3.7/dist-packages/mrcnn/model.py in &lt;module&gt;()
      253 
      254 
  --&gt; 255 class ProposalLayer(KE.Layer):
      256     &quot;&quot;&quot;Receives anchor scores and selects a subset to pass as proposals
      257     to the second stage. Filtering is done based on anchor scores and
  
  AttributeError: module 'keras.engine' has no attribute 'Layer'
  </code></pre>