title: class attribute considered abstract method in python 2.7 - abc module
body: <p>I am trying to implement an abstract superclass (Base) with an abstract method (addfeature), which the Child class will override.</p>
  
  <pre><code>from lxml.builder import ElementMaker
  from abc import ABCMeta, abstractmethod
  
  class Base(object):
      __metaclass__ = ABCMeta
  
      ns = "http://www.foo.com/bar"
      em = ElementMaker(namespace=ns, nsmap={'bar': ns})
  
      @abstractmethod
      def addfeature(self):
          pass
  
  class Child(Base):
      def addfeature(self):
          pass
  
  child_instance = Child()
  </code></pre>
  
  <p>This code fails however with </p>
  
  <blockquote>
    <p>"TypeError: Can't instantiate abstract class Child with abstract
    methods em"</p>
  </blockquote>
  
  <p>Why? em is supposed to be a class attribute, not a method (and surely not an abstract method)</p>