title: Normalise all elements in deep nested list Python
body: <p>I have image data in the form of a deep nested list of ints:</p>
  
  <pre><code>len(train_data_imgs) = 3889       # number of images in set
  len(train_data_imgs[0]) = 100     # height
  len(train_data_imgs[0][0]) = 100  # width
  len(train_data_imgs[0][0][0]) = 3 # these are ints - RGB pixel values
  </code></pre>
  
  <p>How can I iterate through these to normalise them between 0 and 1? Simply would require every number to be divided by 255.</p>