title: Merging many arrays from Promise.all
body: <p>When <code>Promise.all</code> completes it returns an array of arrays that contain data. In my case the arrays are just numbers:</p>
  
  <pre><code>[
      [ 1, 4, 9, 9 ],
      [ 4, 4, 9, 1 ],
      [ 6, 6, 9, 1 ]
  ]
  </code></pre>
  
  <p>The array can be any size.</p>
  
  <p>Currently I'm doing this:</p>
  
  <pre><code>let nums = []
  data.map(function(_nums) {
      _nums.map(function(num) {
          nums.push(num)
      })
  })
  </code></pre>
  
  <p>Is there an alternative way of doing this? Does <code>lodash</code> have any functions that are able to do this?</p>