title: regarding set_image_dim_ordering('tf') in keras
body: <p>When experimenting with a Keras implementation, I did as follows:</p>
  
  <pre><code>from keras import backend as K
  K.set_image_dim_ordering('tf') 
  </code></pre>
  
  <p>It generates the following error message. What does it mean? I think set_image_dim_ordering is included in Keras.</p>
  
  <pre><code>File "train.py", line 14, in &lt;module&gt;
  K.set_image_dim_ordering('tf')
  </code></pre>
  
  <p>AttributeError: 'module' object has no attribute 'set_image_dim_ordering'</p>