what is the difference between [[],[]] and [[]] * 2
<pre><code>t0 = [[]] * 2                                                                   
t1 = [[], []]                                                                   

t0[0].append('hello')                                                           
print t0                                                                        

t1[0].append('hello')                                                           
print t1             
</code></pre>

<p>The result is</p>

<pre><code>[['hello'], ['hello']]
[['hello'], []]
</code></pre>

<p>But I can't tell their difference.</p>
