title: "No module named abc_base"
body: <p>I'm trying to implement an abstract class in python (actually in a django app) and am running up against this madness:</p>
  
  <pre><code>&gt;python concreteChildClass.py
  Traceback (most recent call last):
      File"concreteChildClass.py, line 1, in &lt;module&gt;
          from abc_base import AbstractBaseClass
  ImportError: No module named abc_base
  </code></pre>
  
  <p>I've boiled down my problem to these files that reproduce the error in my env:</p>
  
  <p>abstractBaseClass.py</p>
  
  <pre><code>import abc
  
  class abstractBaseClass(object):
      __metaclass__ = abc.ABCMeta
  
      @abc.abstractmethod
      def load(self, input):
      """Retrieve data from the input source and return an object."""
          return
  </code></pre>
  
  <p>concreteChildClass.py</p>
  
  <pre><code>from abc_base import AbstractBaseClass
  
  class ConcreteChildClass(object):
      def load(self, input):
          return input.read()
  </code></pre>
  
  <p>Here is my python version info </p>
  
  <pre><code>&gt;&gt;&gt; import sys
  &gt;&gt;&gt; print sys.version
  2.7.3 (default, Jan  2 2013, 13:56:14)
  [GCC 4.7.2]
  </code></pre>
  
  <p>I'm fairly new to python (as this question may make painfully obvious), but I can't figure out how 'abc' would be found but not 'abc_base'.  My reading and googling has lead me to no answers on this one.  Thanks in advance and apologies if this is a silly question.</p>