docs: def json(self, dict=False, **kwargs):
          """
          Outputs NetJSON format
          """
          try:
              graph = self.graph
          except AttributeError:
              raise NotImplementedError()
          return _netjson_networkgraph(self.protocol,
                                       self.version,
                                       self.revision,
                                       self.metric,
                                       graph.nodes(data=True),
                                       graph.edges(data=True),
                                       dict,
                                       **kwargs)