title: Is there any easy way in DolphinDB to accomplish what the **shift down** function does in Python?
body: <p>Is there any easy way in DolphinDB to accomplish what the <strong>shift down</strong> function does in Python?</p>
  <p>Say I have a matrix that is 3x3:</p>
  <pre><code>#0 #1 #2
  -- -- --
  1  4  7 
  2  5  8 
  3  6  9
  </code></pre>
  <p>I want to shift one row down in a matrix as follow:</p>
  <pre><code>#0 #1 #2
  -- -- --
          
  1  4  7 
  2  5  8 
  </code></pre>
  <p>How can this be done in DolphinDB?
  Thanks for advance</p>