Python method parameter list
<p>in a method definition why would someone set the formal parameter <code>amount</code> equal to the constant <code>PERMANENCE_INC</code> in the formal parameter list?</p>

<pre><code>def increasePermanence(self, amount=PERMANENCE_INC): 
    """ Increases the permanence of this synapse. """ 
    self.permanence = min(1.0, self.permanence+amount)
</code></pre>
