title: UnicodeDecodeError error writing .xlsx file using xlsxwriter
body: <p>I am trying to write about 1000 rows to a .xlsx file from my python application. The data is basically a combination of integers and strings. I am getting intermittent error while running wbook.close() command. The error is the following:</p>
  
  <pre><code>UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 15: 
                       ordinal not in range(128)
  </code></pre>
  
  <p>My data does not have anything in unicode. I am wondering why the decoder is being at all. Has anyone noticed this problem?</p>