code: def control_circuit_breakers(self, mode=None):
          
  
          for grid_district in self.mv_grid_districts():
              if mode == 'open':
                  grid_district.mv_grid.open_circuit_breakers()
              elif mode == 'close':
                  grid_district.mv_grid.close_circuit_breakers()
              else:
                  raise ValueError('\'mode\' is invalid.')
  
          if mode == 'open':
              logger.info('=====> MV Circuit Breakers opened')
          elif mode == 'close':
              logger.info('=====> MV Circuit Breakers closed')
docs: Opens or closes all circuit breakers of all MV grids.
  
          Args
          ----
          mode: str
              Set mode='open' to open, mode='close' to close