If you have libreoffice installed, you can do a python execution wrapper around its headless mode:
$ /usr/bin/libreoffice --headless --invisible -convert-to ods /home/cwgem/Downloads/QTL_Sample_data.xls
convert /home/cwgem/Downloads/QTL_Sample_data.xls -> /home/cwgem/QTL_Sample_data.ods using OpenDocument Spreadsheet Flat XML
$ /usr/bin/libreoffice --headless --invisible -convert-to xls /home/cwgem/QTL_Sample_data.ods
convert /home/cwgem/QTL_Sample_data.ods -> /home/cwgem/QTL_Sample_data.xls using
Which would be a bit easier than trying to do it through the library route.