title: Can't instantiate abstract class ... with abstract methods
body: <p>I'm working on a kind of lib, and for a weird reason i have this error. </p>
  
  <ul>
  <li><a href="https://github.com/josuebrunel/yahoo-fantasy-sport/blob/master/fantasy_sport/roster.py" rel="noreferrer">Here</a> is my code. Of course <em>@abc.abstractmethod have to be uncommented</em></li>
  <li><a href="https://github.com/josuebrunel/yahoo-fantasy-sport/blob/master/tests.py#L206-247" rel="noreferrer">Here</a> are my tests</li>
  </ul>
  
  <p><em>Sorry couldn't just copy and paste it</em></p>
  
  <p>I went on the basis that the code below works </p>
  
  <p><em>test.py</em></p>
  
  <pre><code>import abc
  import six
  
  @six.add_metaclass(abc.ABCMeta)
  class Base(object):
  
      @abc.abstractmethod
      def whatever(self,):
          raise NotImplementedError
  
  class SubClass(Base):
  
      def __init__(self,):
  
          super(Base, self).__init__()
          self.whatever()
  
      def whatever(self,):
          print("whatever")
  </code></pre>
  
  <p>In the python shell</p>
  
  <pre><code>&gt;&gt;&gt; from test import *
  &gt;&gt;&gt; s = SubClass()
  whatever
  </code></pre>
  
  <p>Why for my <em>roster</em> module i'm having this error</p>
  
  <pre><code>Can't instantiate abstract class Player with abstract methods _Base__json_builder, _Base__xml_builder
  </code></pre>
  
  <p>Thanks in advance </p>