Python: Reference of lists
<p>I tried to put this line in my code, attempting to create a 80*80 grid:</p>

<pre><code>a = [[0] * 80] * 80
</code></pre>

<p>However, it turned out that I have 80 reference to the same lists, and it took me really long to realize this problem. </p>

<p>I am wondering is there a way to understand/memorize how python reference in common methods?</p>

<p>Thanks!</p>
