title: Indentation not working properly in emacs for python
body: <p>I am using emacs-for-python provided  by gabrielelanaro at this <a href="https://github.com/gabrielelanaro/emacs-for-python">link</a>. </p>
  
  <p>Indentation doesn't seem to be working for me at all.</p>
  
  <p>It doesn't happen automatically when I create a class, function or any other block of code that requires automatic indentation(if, for etc.) and press enter or <code>Ctrl + j</code>. Instead emacs says "Arithmetic Error".</p>
  
  <p>It doesn't happen when I press <code>Tab</code> anywhere in a .py file. Again, every <code>Tab</code> press causes "Arithmetic error". </p>
  
  <p>Also, when I manually indent code using spaces, I can't erase those spaces! Backspace-ing these indents also causes "Arithmetic Error".</p>
  
  <p>This problem surfaces when I use the regular <code>Python AC</code> mode as well.</p>
  
  <p>emacs : GNU Emacs 24.3.1 (x86_64-pc-linux-gnu, GTK+ Version 3.10.7)
   of 2014-03-07 on lamiak, modified by Debian</p>