Replace all zeros in array with elements of another array
<p>Say I've got an array like this:</p>

<pre><code>array_1 =  [0, 0, 1, 2, 3, 0]
</code></pre>

<p>and another one like this:</p>

<pre><code>array_2 = [4, 5, 6]
</code></pre>

<p>How can I create an array like this, such that each 0 in the <code>array_1</code> is replaced by the first and subsequent elements of the <code>array_2</code>?:</p>

<p><code>[4, 5, 1, 2, 3, 6]</code></p>

<p>That is, every time we encounter a <code>0</code> in the first array, we'd like to replace it with the result of <code>array_2.shift</code>.</p>