title: Error when calling the metaclass bases: function() argument 1 must be code, not str
body: <p>I tried to subclass threading.Condition earlier today but it didn't work out. Here is the output of the Python interpreter when I try to subclass the threading.Condition class:</p>
  
  <pre><code>&gt;&gt;&gt; import threading
  &gt;&gt;&gt; class ThisWontWork(threading.Condition):
  ...     pass
  ... 
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  TypeError: Error when calling the metaclass bases
      function() argument 1 must be code, not str
  </code></pre>
  
  <p>Can someone explain this error?  Thanks!</p>