title: Line is too long. Django PEP8
body: <p>PEP8 info:    </p>
  
  <pre><code>models.py:10:80: E501 line too long (83 &gt; 79 characters)
  </code></pre>
  
  <p>Models.py:    </p>
  
  <pre><code>field = TreeForeignKey('self', null=True, blank=True, related_name='abcdefgh')
  </code></pre>
  
  <p>How to correctly write this line?</p>