Uninstantiated class attribute
<p>Hello I need an uninstantiated class attribute and I am doing this:</p>

<pre><code>&gt;&gt;&gt; class X:
...     def __init__(self, y=None):
...             self.y = list()
</code></pre>

<p>Is this ok? If no, is there another way of doing it. I can't instantiate this attribute in <code>__init__</code> cause I would be appending to this later.</p>
