title: Python 3.6.5 "Multiple bases have instance lay-out conflict" when multi-inheritance of classes having __slots__
body: <p>If I run this code, I'v got the subject error message. But why? And how to avoid it getting the <code>C</code> class having its parents slots?</p>
  
  <pre><code>class A():
          __slots__ = ['slot1']
  
  class B():
          __slots__ = ['slot2']
  
  class C(A, B):
          __slots__ = []
  </code></pre>