code: def export_csv_file(self, directory, filename):
          
          bpmn_csv_export.BpmnDiagramGraphCsvExport.export_process_to_csv(self, directory, filename)
docs: Exports diagram inner graph to BPMN 2.0 XML file (with Diagram Interchange data).
  
          :param directory: strings representing output directory,
          :param filename: string representing output file name.