title: Python append xls file using only xlwt/xlrd
body: <p>I am having problems appending issues appending data to an <code>xls</code> file.
  Long story short, I am using a program to get some data from something and writing it in an <code>xls</code> file. </p>
  
  <p>If I run the script 10 times, I would like the results to be appended to the same xls file. </p>
  
  <p>My problem is that I am forced to use Python 3.4 and <code>xlutils</code> is not supported, so I cannot use the copy function. </p>
  
  <p>I just have to use <code>xlwt</code> / <code>xlrd</code>. Note, the file cannot be a <code>xlsx</code>.</p>
  
  <p>Is there any way i can do this?</p>