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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def export_node(bpmn_graph, export_elements, node, nodes_classification, order=0, prefix="", condition="", who="", add_join=False):
 """ General method for node exporting :param bpmn_graph: an instance of BpmnDiagramGraph class, :param export_elements: a dictionary object. The key is a node ID, value is a dictionary of parameters that will be used in exported CSV document, :param node: networkx.Node object, :param nodes_classification: dictionary of classification labels. Key - node id. Value - a list of labels, :param order: the order param of exported node, :param prefix: the prefix of exported node - if the task appears after some gateway, the prefix will identify the branch :param condition: the condition param of exported node, :param who: the condition param of exported node, :param add_join: boolean flag. Used to indicate if "Join" element should be added to CSV. :return: None or the next node object if the exported node was a gateway join. """

        node_type = node[1][consts.Consts.type]
        if node_type == consts.Consts.start_event:
            return BpmnDiagramGraphCsvExport.export_start_event(bpmn_graph, export_elements, node, nodes_classification,
                                                                order=order, prefix=prefix, condition=condition,
                                                                who=who)
        elif node_type == consts.Consts.end_event:
            return BpmnDiagramGraphCsvExport.export_end_event(export_elements, node, order=order, prefix=prefix,
                                                              condition=condition, who=who)
        else:
            return BpmnDiagramGraphCsvExport.export_element(bpmn_graph, export_elements, node, nodes_classification,
                                                            order=order, prefix=prefix, condition=condition, who=who,
                                                            add_join=add_join)