title: how to import from parallel directory in pycharm with python 2.7
body: <p>I get a directory like the following:</p>
  
  <pre><code>__init__.py
  common
  |      \
  |      __init__.py
  |      util.py
  |     
  sites
      \
       __init__.py
       site_a.py
  </code></pre>
  
  <p>The folder where 'common' and 'sites' locat  is named 'father'
  I'd like to import common/util.py from inside sites/site_a.py.
  I tried to use: from father.common import util
  But pycharm reports: unsolved reference 'father'</p>
  
  <p>How shall I import util.py from inside site_a.py?
  PS: I don't want to change my PYTHONPATH setting, so please use correct python codes only.</p>