docs: def exportTree(self, tree, filename):
          """
          Exports the inputed tree object to the given excel file.
          
          :param      tree     | <QTreeWidget>
                      filename | <str>
          
          :return     <bool>
          """
          book = xlwt.Workbook()
          
          # determine the title for the sheet to export
          title = nativestring(tree.windowTitle())
          if not title:
              title = nativestring(tree.objectName())
          if not title:
              title = 'Sheet 1'
          
          sheet = book.add_sheet(title)
          
          # determine visible columns to export
          cols = [c for c in range(tree.columnCount()) \
                  if not tree.isColumnHidden(c)]
          
          # export the column headers
          hitem = tree.headerItem()
          for c, col in enumerate(cols):
              sheet.write(0, c, nativestring(hitem.text(col)))
          
          self._currrow = 1
          for i in range(tree.topLevelItemCount()):
              self.exportTreeItem(sheet, cols, tree.topLevelItem(i))
          
          book.save(filename)
          return True