title: ImportError: No module named 'util'
body: <p>I know that there are many variations of this question, but I could not find one like mine. When I try to import the module <code>illustris_python</code> I get the error <code>ImportError: No module named 'util'</code> The module util is in the directory below the module <code>snapshot.py</code> that needs it so I am confused as to why python sees one module , but not the other.
   I have included the import call as well as traceback below. </p>
  
  <pre><code>Python 3.4.3 (v3.4.3:9b73f1c3e601, Feb 24 2015, 22:44:40) [MSC v.1600 64 bit (AMD64)]
  Type "copyright", "credits" or "license" for more information.
  
  IPython 3.0.0 -- An enhanced Interactive Python.
  ?         -&gt; Introduction and overview of IPython's features.
  %quickref -&gt; Quick reference.
  help      -&gt; Python's own help system.
  object?   -&gt; Details about 'object', use 'object??' for extra details.
  %guiref   -&gt; A brief reference about the graphical user interface.
  
  In [1]: import illustris_python as il
  Traceback (most recent call last):
  
    File "&lt;ipython-input-1-ff06d24b4811&gt;", line 1, in &lt;module&gt;
      import illustris_python as il
  
    File "C:\WinPython-64bit-3.4.3.2\python-3.4.3.amd64\lib\site-     packages\illustris_python\__init__.py", line 3, in &lt;module&gt;
      from . import *
  
    File "C:\WinPython-64bit-3.4.3.2\python-3.4.3.amd64\lib\site- packages\illustris_python\snapshot.py", line 6, in &lt;module&gt;
      from util import partTypeNum
  
  ImportError: No module named 'util'
  
  
  In [2]: 
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/G0EVq.png" alt="Screen shot showing location of util"></p>