title: Calling superclass constructors in python with different arguments
body: <pre><code>class A():
      def __init__( self, x, y):
          self.x = x
          self.y = y
  
  class B():
      def __init__( self, z=0):
          self.z = z  
  
  class AB(A,B):
      def __init__( self, x, y, z=0):
          ?
  </code></pre>
  
  <p>How can I make the constructor of AB call the constructors for A and B with the proper arguments?</p>
  
  <p>I've tried</p>
  
  <pre><code>class AB(A,B):
      def __init__( self, x, y, z=0):
          A.__init__(x,y)
          B.__init__(z)
  </code></pre>
  
  <p>but this gives me an error.</p>