def save doc, to_filename, &data_iterator

      @file_manager = OfficeFileManager.new(@ods_template)
      
      data_iterator.call(doc)

      @file_manager.save doc, to_filename
      
    end
def save doc, to_filename, &data_iterator

      @file_manager = OfficeFileManager.new(@ods_template)
      
      data_iterator.call(doc)

      @file_manager.save doc, to_filename
      
    end
output is a String (as a file name)