title: Can lodash remove arrays containing only null or undefined?
body: <p>I have a data object that looks like this:</p>
  
  <pre><code>var obj = {
      "one":      null,
      "two":      undefined,
      "three":    [undefined],
      "four":     "valid value"
  }
  </code></pre>
  
  <p>And I need to end up with this:</p>
  
  <pre><code>{
      "four":     "valid value"
  }
  </code></pre>
  
  <p>I'm using lodash to try and accomplish this, and it's gotten me part way there:</p>
  
  <pre><code>obj = _.pick(obj, _identity);
  </code></pre>
  
  <p>Which gives me:</p>
  
  <pre><code>{
      "three":    [undefined],
      "four":     "valid value"
  }
  </code></pre>
  
  <p>Is there a lodash-centric way to also remove not only keys whose values are null or undefined and also remove keys whose values are arrays that contain only undefined or null? I know there's a bunch of ways to do this in general, I was just wondering if lodash had some way to do this baked in.</p>