title: dict_keys object does not support indexing
body: <p>I have no idea what is the problem here:</p>
  
  <pre><code>net.blobs['data'].reshape(*(1, 3, imageToTest_padded.shape[0], imageToTest_padded.shape[1]))
  #net.forward() # dry run
  net.blobs['data'].data[...] = np.transpose(np.float32(imageToTest_padded[:,:,:,np.newaxis]), (3,2,0,1))/256 - 0.5;
  start_time = time.time()
  output_blobs = net.forward()
  print('At scale %d, The CNN took %.2f ms.' % (m, 1000 * (time.time() - start_time)))
  
  # extract outputs, resize, and remove padding
  heatmap = np.transpose(np.squeeze(net.blobs[output_blobs.keys()[1]].data), (1,2,0))  # output 1 is heatmaps
  heatmap = cv.resize(heatmap, (0,0), fx=model['stride'], fy=model['stride'], interpolation=cv.INTER_CUBIC)
  heatmap = heatmap[:imageToTest_padded.shape[0]-pad[2], :imageToTest_padded.shape[1]-pad[3], :]
  heatmap = cv.resize(heatmap, (oriImg.shape[1], oriImg.shape[0]), interpolation=cv.INTER_CUBIC)
  </code></pre>
  
  <p>Getting an error TypeError: 'dict_keys' object does not support indexing in line</p>
  
  <pre><code>heatmap = np.transpose(np.squeeze(net.blobs[output_blobs.keys()[1]].data), (1,2,0))  # output 1 is heatmaps
  </code></pre>
  
  <p>Original code: <a href="https://github.com/ZheC/Realtime_Multi-Person_Pose_Estimation" rel="nofollow noreferrer">https://github.com/ZheC/Realtime_Multi-Person_Pose_Estimation</a></p>
  
  <p>Any suggestions? Thanks.</p>