title: Convert array of single-element arrays to a one-dimensional array
body: <p>I have this kind of an array containing single-element arrays:</p>
  <pre><code>$array = [[88868], [88867], [88869], [88870]];
  </code></pre>
  <p>I need to convert this to one dimensional array.</p>
  <p>Desired output:</p>
  <pre><code>[88868, 88867, 88869, 88870]
  </code></pre>
  <p>Is there any built-in/native PHP functionality for this array conversion?</p>