title: Renaming imports when there is no need
body: <p>Reading through the google style guide for python i saw this:</p>
  <pre><code>import tensorflow as tf
  </code></pre>
  <p>I've also seen similar with say numpy:</p>
  <pre><code>import numpy as np
  </code></pre>
  <p>I understand that it's for name collision resolution, but i've seen it used even when it's the only import/variable with that name.
  Why?</p>