Why should multidimensional arrays be constructed with for loops?
<pre><code>def make_set(rad):
    y = []
    for i in range(0, rad):
        x = []
        for j in range(0, rad):
            x.append(0)
        y.append(x)
    return y

def make_set_basic(rad):
    z = [[0] * rad] * rad
    return z
</code></pre>

<p>What is problematic about the latter implementation (make_set_basic)? </p>
