code: def _check_Vn(self):
          
          if hasattr(self, 'bus') and hasattr(self, 'Vn'):
              bus_Vn = self.read_data_ext('Bus', field='Vn', idx=self.bus)
              for name, bus, Vn, Vn0 in zip(self.name, self.bus, self.Vn,
                                            bus_Vn):
                  if Vn != Vn0:
                      self.log(
                          '<{}> has Vn={} different from bus <{}> Vn={}.'.format(
                              name, Vn, bus, Vn0), WARNING)
  
          if hasattr(self, 'node') and hasattr(self, 'Vdcn'):
              node_Vdcn = self.read_data_ext('Node', field='Vdcn', idx=self.node)
              for name, node, Vdcn, Vdcn0 in zip(self.name, self.node, self.Vdcn,
                                                 node_Vdcn):
                  if Vdcn != Vdcn0:
                      self.log(
                          '<{}> has Vdcn={} different from node <{}> Vdcn={}.'
                          .format(name, Vdcn, node, Vdcn0), WARNING)
docs: Check data consistency of Vn and Vdcn if connected to Bus or Node
  
          :return None