title: __abstractmethods__ and AttributeError
body: <p>I was playing with the <code>dir()</code> builtin function when I noticed this:</p>
  
  <pre><code>&gt;&gt;&gt; dir(type)
  ['__abstractmethods__', '__base__', '__bases__', '__basicsize__', '__call__', '__class__', '__delattr__', '__dict__', '__dictoffset__', '__dir__', '__doc__', '__eq__', '__flags__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__instancecheck__', '__itemsize__', '__le__', '__lt__', '__module__', '__mro__', '__name__', '__ne__', '__new__', '__prepare__', '__qualname__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasscheck__', '__subclasses__', '__subclasshook__', '__text_signature__', '__weakrefoffset__', 'mro']
  &gt;&gt;&gt; type.__abstractmethods__
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  AttributeError: __abstractmethods__
  &gt;&gt;&gt; list.__abstractmethods__
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  AttributeError: __abstractmethods__
  </code></pre>
  
  <p>I don't understand, it appears in the list, why am I getting such error?</p>