code: def import_participant_element(diagram_graph, participants_dictionary, participant_element):
          
          participant_id = participant_element.getAttribute(consts.Consts.id)
          name = participant_element.getAttribute(consts.Consts.name)
          process_ref = participant_element.getAttribute(consts.Consts.process_ref)
          if participant_element.getAttribute(consts.Consts.process_ref) == '':
              diagram_graph.add_node(participant_id)
              diagram_graph.node[participant_id][consts.Consts.type] = consts.Consts.participant
              diagram_graph.node[participant_id][consts.Consts.process] = participant_id
          participants_dictionary[participant_id] = {consts.Consts.name: name, consts.Consts.process_ref: process_ref}
docs: Adds 'participant' element to the collaboration dictionary.
  
          :param diagram_graph: NetworkX graph representing a BPMN process diagram,
          :param participants_dictionary: dictionary with participant element attributes. Key is participant ID, value
             is a dictionary of participant attributes,
          :param participant_element: object representing a BPMN XML 'participant' element.