code: def newton_call(self):
          
          # system = self.system
          # exec(system.call.newton)
  
          system = self.system
          dae = self.system.dae
  
          system.dae.init_fg()
          system.dae.reset_small_g()
          # evaluate algebraic equation mismatches
          for model, pflow, gcall in zip(system.devman.devices,
                                         system.call.pflow, system.call.gcall):
              if pflow and gcall:
                  system.__dict__[model].gcall(dae)
  
          # eval differential equations
          for model, pflow, fcall in zip(system.devman.devices,
                                         system.call.pflow, system.call.fcall):
              if pflow and fcall:
                  system.__dict__[model].fcall(dae)
  
          # reset islanded buses mismatches
          system.Bus.gisland(dae)
  
          if system.dae.factorize:
              system.dae.init_jac0()
              # evaluate constant Jacobian elements
              for model, pflow, jac0 in zip(system.devman.devices,
                                            system.call.pflow, system.call.jac0):
                  if pflow and jac0:
                      system.__dict__[model].jac0(dae)
              dae.temp_to_spmatrix('jac0')
  
          dae.setup_FxGy()
  
          # evaluate Gy
          for model, pflow, gycall in zip(system.devman.devices,
                                          system.call.pflow, system.call.gycall):
              if pflow and gycall:
                  system.__dict__[model].gycall(dae)
  
          # evaluate Fx
          for model, pflow, fxcall in zip(system.devman.devices,
                                          system.call.pflow, system.call.fxcall):
              if pflow and fxcall:
                  system.__dict__[model].fxcall(dae)
  
          # reset islanded buses Jacobians
          system.Bus.gyisland(dae)
  
          dae.temp_to_spmatrix('jac')
docs: Function calls for Newton power flow
  
          Returns
          -------
          None