title: print two dimensional list
body: <p>I have a list, in which is another list and I want to <code>doc.write(a)</code></p>
  
  <pre><code>a = [[1, 2, "hello"],
       [3, 5, "hi There"],
       [5,7,"I don't know"]]
  doc.write(''.join(a))
  
  
  
  TypeError: sequence item 0: expected str instance, list found
  </code></pre>
  
  <p>How can I handle this, do I have to make a for-loop in which I join and add all the sublists?</p>
  
  <p>The real goal was to make it somehow readable for human beeing, but I didn't wanted a finished solution from you.</p>