code: def _intf_network(self):
          
  
          for key, val in self._ac.items():
              self.copy_data_ext(
                  model='Bus', field='a', dest=val[0], idx=self.__dict__[key])
              self.copy_data_ext(
                  model='Bus', field='v', dest=val[1], idx=self.__dict__[key])
  
          for key, val in self._dc.items():
              self.copy_data_ext(
                  model='Node', field='v', dest=val, idx=self.__dict__[key])
  
          # check for interface voltage differences
          self._check_Vn()
docs: Retrieve the ac and dc network interface variable indices.
  
          :Example:
  
              ``self._ac = {'bus1': (a1, v1)}`` gives
               - indices: self.bus1
               - system.Bus.a -> self.a1
               - system.Bus.v -> self.v1
  
              ``self._dc = {'node1': v1}`` gives
                - indices: self.node1
                - system.Node.v-> self.v1
  
          :return: None