title: How do I check (at runtime) if one class is a subclass of another?
body: <p>Let's say that I have a class Suit and four subclasses of suit: Heart, Spade, Diamond, Club.</p>
  
  <pre><code>class Suit:
     ...
  class Heart(Suit):
     ...
  class Spade(Suit):
     ...
  class Diamond(Suit):
     ...
  class Club(Suit):
     ...
  </code></pre>
  
  <p>I have a method which receives a suit as a parameter, which is a class object, not an instance. More precisely, it may receive only one of the four values: Heart, Spade, Diamond, Club. How can I make an assertion which ensures such a thing? Something like:</p>
  
  <pre><code>def my_method(suit):
     assert(suit subclass of Suit)
     ...
  </code></pre>
  
  <p>I'm using Python 3.</p>