title: FILTER 2 columns into one with NOT(ISBLANK)
body: <p>I have two columns which I want to convert into 1 column, but not showing the blanks.
  e.g.</p>
  
  <pre><code>|---------------------|------------------|
  |      Column 1       |     Column 2     |
  |---------------------|------------------|
  |       Test1         |      Test2       |
  |---------------------|------------------|
  |                     |                  |
  |---------------------|------------------|
  |       Test4         |      Test3       |
  |---------------------|------------------|
  </code></pre>
  
  <p>Expected result:</p>
  
  <pre><code>|---------------------|
  |      Column 1       |
  |---------------------|
  |       Test1         |
  |---------------------|
  |       Test2         |
  |---------------------|
  |       Test3         |
  |---------------------|
  |       Test4         |
  |---------------------|
  </code></pre>
  
  <p>My best bet would be using this formula, but it is not working.</p>
  
  <pre><code>=FILTER({E6:G17,E22:G33},NOT(ISBLANK({E6:G17,E22:G33})))
  </code></pre>
  
  <p>Can you guys help me out?</p>