Whats happening here? : <pre><code>z=[0 for i in range(3)]
print(z) # [0,0,0]
x=[z for i in range(3)]
print(x) #[[0,0,0],[0,0,0],[0,0,0]]
x[1][1]=7
print(x) #[[0,7,0],[0,7,0],[0,7,0]]
</code></pre>

<p>Can someone explain what's happening here?</p>
