code: def gisland(self, dae):
          
          if not (self.islanded_buses and self.island_sets):
              return
  
          a, v = list(), list()
  
          # for islanded areas without a slack bus
          for island in self.island_sets:
              nosw = 1
              for item in self.system.SW.bus:
                  if self.uid[item] in island:
                      nosw = 0
                      break
              if nosw:
                  self.islanded_buses += island
                  self.island_sets.remove(island)
  
          a = self.islanded_buses
          v = [self.n + item for item in a]
          dae.g[a] = 0
          dae.g[v] = 0
docs: Reset g(x) for islanded buses and areas