title: Add Commas Between Elements
body: <p>I have a data structure that looks like this:</p>
  
  <pre><code>[[     date     person  
    0    1/1/2018 john   
    1    1/3/2018 jane   
    2    1/9/2018 john ]
   [     date     person  
    0    2/1/2018 john   
    1    2/3/2018 jane   
    2    2/9/2018 john ]]
  </code></pre>
  
  <p>It is a list of lists, but there are no commas between each element in the list. </p>
  
  <p>Therefore, when attempting to convert the list to a <code>pandas</code> <code>DataFrame</code>, assertion errors occur because the nested list is technically one column, whereas the target <code>df</code> is two columns.</p>
  
  <p>How would I add commas to the nested list or otherwise convert it into a <code>df</code> that looks like the one below?</p>
  
  <pre><code>date      person
  1/1/2018  john
  1/3/2018  jane
  1/9/2018  john
  2/1/2018  john
  2/3/2018  jane
  2/9/2018  john
  </code></pre>