Class attribute or argument's default value
<p>I've found the following open source code in Python:</p>

<pre><code>class Wait:

  timeout = 9

  def __init__(self, timeout=None):

    if timeout is not None:
        self.timeout = timeout
    ...
</code></pre>

<p>I'm trying to understand if there are advantages of the code above vs using default argument's value:</p>

<pre><code>class Wait:

   def __init__(self, timeout=9):
     ...
</code></pre>
