code: def export_lane_set(process, lane_set, plane_element):
          
          lane_set_xml = eTree.SubElement(process, consts.Consts.lane_set)
          for key, value in lane_set[consts.Consts.lanes].items():
              BpmnDiagramGraphExport.export_lane(lane_set_xml, key, value, plane_element)
docs: Creates 'laneSet' element for exported BPMN XML file.
  
          :param process: an XML element ('process'), from exported BPMN 2.0 document,
          :param lane_set: dictionary with exported 'laneSet' element attributes and child elements,
          :param plane_element: XML object, representing 'plane' element of exported BPMN 2.0 XML.