title: How can I reduce or flatten an array of arrays using the Array.concat() method inside the callback function for Array.reduce()
body: <pre><code>
  //Bonus - uncomment lines 15 and 17
  const arrays = [["how", "now"], ["brown", "cow"]];
  const flattenedArray = arrays.reduce((a,c) =&gt; a + c);
  // The below line should console.log: ["how", "now", "brown", "cow"]
  console.log(flattenedArray);
  
  </code></pre>
  
  <p>I'm new to using the reduce function and it's a little bit complicated.</p>
  
  <p>I'm trying to flatten the nested array but I don't really know what to do next. </p>