title: python subclasscheck & subclasshook
body: <p>The methods <code>__subclasscheck__</code> and <code>__subclasshook__</code> are used to determine if a class is regarded as subclass of another. However, their documentation is very limited, even in advanced Python books. How are they meant to be used and what is their difference (higher priority, side of relationship they refer to etc...)?</p>