How to use the pyomo.network.Arc function in Pyomo

source=m.fs.turb.lp_split[11].outlet_2, destination=m.fs.fwh1.drain_mix.steam
    )
    m.fs.COND_03 = Arc(
        source=m.fs.cond_pump.outlet, destination=m.fs.fwh1.condense.inlet_2
    )
    m.fs.FWH1_DRN1 = Arc(
        source=m.fs.fwh1.condense.outlet_1, destination=m.fs.fwh1_pump.inlet
    )
    m.fs.FWH1_DRN2 = Arc(
        source=m.fs.fwh1_pump.outlet, destination=m.fs.fwh1_return.fwh1_drain
    )
    m.fs.FW01A = Arc(
        source=m.fs.fwh1.condense.outlet_2, destination=m.fs.fwh1_return.feedwater
    )
    # fwh2
    m.fs.FW01B = Arc(
        source=m.fs.fwh1_return.outlet, destination=m.fs.fwh2.cooling.inlet_2
    )
    m.fs.FWH2_DRN = Arc(
        source=m.fs.fwh2.cooling.outlet_1, destination=m.fs.fwh1.drain_mix.drain
    )
    m.fs.EXTR_LP10 = Arc(
        source=m.fs.turb.lp_split[10].outlet_2,
        destination=m.fs.fwh2.desuperheat.inlet_1,
    )
    # fwh3
    m.fs.FW02 = Arc(
        source=m.fs.fwh2.desuperheat.outlet_2, destination=m.fs.fwh3.cooling.inlet_2
    )
    m.fs.FWH3_DRN = Arc(
        source=m.fs.fwh3.cooling.outlet_1, destination=m.fs.fwh2.drain_mix.drain
    )

############################################################################
    #  High-pressure feedwater heaters                                         #
    ############################################################################
    # fwh6
    m.fs.FW05B = Arc(source=m.fs.bfp.outlet, destination=m.fs.fwh6.cooling.inlet_2)
    m.fs.FWH6_DRN = Arc(
        source=m.fs.fwh6.cooling.outlet_1, destination=m.fs.fwh5_da.drain
    )
    m.fs.EXTR_IP5 = Arc(
        source=m.fs.turb.ip_split[5].outlet_2, destination=m.fs.fwh6.desuperheat.inlet_1
    )
    # fwh7
    m.fs.FW06 = Arc(
        source=m.fs.fwh6.desuperheat.outlet_2, destination=m.fs.fwh7.cooling.inlet_2
    )
    m.fs.FWH7_DRN = Arc(
        source=m.fs.fwh7.cooling.outlet_1, destination=m.fs.fwh6.drain_mix.drain
    )
    m.fs.EXTR_HP7 = Arc(
        source=m.fs.turb.hp_split[7].outlet_2, destination=m.fs.fwh7.desuperheat.inlet_1
    )
    # fwh8
    m.fs.FW07 = Arc(
        source=m.fs.fwh7.desuperheat.outlet_2, destination=m.fs.fwh8.cooling.inlet_2
    )
    m.fs.FWH8_DRN = Arc(
        source=m.fs.fwh8.cooling.outlet_1, destination=m.fs.fwh7.drain_mix.drain
    )
    m.fs.EXTR_HP4 = Arc(
        source=m.fs.turb.hp_split[4].outlet_2, destination=m.fs.fwh8.desuperheat.inlet_1
    )

m.fs.FW03 = Arc(
        source=m.fs.fwh3.desuperheat.outlet_2, destination=m.fs.fwh4.cooling.inlet_2
    )
    m.fs.FWH4_DRN = Arc(
        source=m.fs.fwh4.cooling.outlet_1, destination=m.fs.fwh3.drain_mix.drain
    )
    m.fs.EXTR_LP4 = Arc(
        source=m.fs.turb.lp_split[4].outlet_2, destination=m.fs.fwh4.desuperheat.inlet_1
    )
    ############################################################################
    #  FWH5 (Deaerator) and boiler feed pump (BFP)                             #
    ############################################################################
    m.fs.FW04 = Arc(
        source=m.fs.fwh4.desuperheat.outlet_2, destination=m.fs.fwh5_da.feedwater
    )
    m.fs.EXTR_IP10 = Arc(
        source=m.fs.turb.ip_split[10].outlet_2, destination=m.fs.fwh5_da.steam
    )
    m.fs.FW05A = Arc(source=m.fs.fwh5_da.outlet, destination=m.fs.bfp.inlet)
    m.fs.EXTR_BFPT_A = Arc(
        source=m.fs.turb.ip_split[10].outlet_3, destination=m.fs.bfpt.inlet
    )
    m.fs.EXHST_BFPT = Arc(source=m.fs.bfpt.outlet, destination=m.fs.condenser_mix.bfpt)
    ############################################################################
    #  High-pressure feedwater heaters                                         #
    ############################################################################
    # fwh6
    m.fs.FW05B = Arc(source=m.fs.bfp.outlet, destination=m.fs.fwh6.cooling.inlet_2)
    m.fs.FWH6_DRN = Arc(
        source=m.fs.fwh6.cooling.outlet_1, destination=m.fs.fwh5_da.drain
    )
    m.fs.EXTR_IP5 = Arc(

# heat loss in the boiler, so actual plant efficiency would be lower.
    @m.fs.Expression(m.fs.time)
    def steam_cycle_eff(b, t):
        return -100 * b.turb.power[t] / b.boiler_heat[t]

    ############################################################################
    ##  Create the stream Arcs                                                ##
    ############################################################################

    ############################################################################
    #  Connect turbine and condenser units                                     #
    ############################################################################
    m.fs.EXHST_MAIN = Arc(
        source=m.fs.turb.outlet_stage.outlet, destination=m.fs.condenser_mix.main
    )
    m.fs.condenser_mix_to_condenser = Arc(
        source=m.fs.condenser_mix.outlet_tpx, destination=m.fs.condenser.inlet_1
    )
    m.fs.COND_01 = Arc(
        source=m.fs.condenser.outlet_1_ph, destination=m.fs.hotwell.condensate
    )
    m.fs.COND_02 = Arc(source=m.fs.hotwell.outlet, destination=m.fs.cond_pump.inlet)
    ############################################################################
    #  Low pressure FWHs                                                       #
    ############################################################################
    m.fs.EXTR_LP11 = Arc(
        source=m.fs.turb.lp_split[11].outlet_2, destination=m.fs.fwh1.drain_mix.steam
    )
    m.fs.COND_03 = Arc(
        source=m.fs.cond_pump.outlet, destination=m.fs.fwh1.condense.inlet_2
    )
    m.fs.FWH1_DRN1 = Arc(

source=m.fs.fwh6.desuperheat.outlet_2, destination=m.fs.fwh7.cooling.inlet_2
    )
    m.fs.FWH7_DRN = Arc(
        source=m.fs.fwh7.cooling.outlet_1, destination=m.fs.fwh6.drain_mix.drain
    )
    m.fs.EXTR_HP7 = Arc(
        source=m.fs.turb.hp_split[7].outlet_2, destination=m.fs.fwh7.desuperheat.inlet_1
    )
    # fwh8
    m.fs.FW07 = Arc(
        source=m.fs.fwh7.desuperheat.outlet_2, destination=m.fs.fwh8.cooling.inlet_2
    )
    m.fs.FWH8_DRN = Arc(
        source=m.fs.fwh8.cooling.outlet_1, destination=m.fs.fwh7.drain_mix.drain
    )
    m.fs.EXTR_HP4 = Arc(
        source=m.fs.turb.hp_split[4].outlet_2, destination=m.fs.fwh8.desuperheat.inlet_1
    )

    ############################################################################
    # Turn the Arcs into constraints and return the model                      #
    ############################################################################
    pyo.TransformationFactory("network.expand_arcs").apply_to(m.fs)
    return m

# deactivate constraints linking the FWH8 to HP turbine
    m.fs.boiler_pressure_drop.deactivate()
    m.fs.close_flow.deactivate()
    m.fs.turb.constraint_reheat_flow.deactivate()
    m.fs.turb.constraint_reheat_press.deactivate()
    m.fs.turb.constraint_reheat_temp.deactivate()
    m.fs.turb.inlet_split.inlet.enth_mol.unfix()
    m.fs.turb.inlet_split.inlet.pressure.unfix()
    # user can fix the boiler feed water pump pressure (uncomenting next line)
#    m.fs.bfp.outlet.pressure[:].fix(26922222.222))

    m.fs.FHWtoECON = Arc(source=m.fs.fwh8.desuperheat.outlet_2,
                         destination=m.fs.ECON.side_1_inlet)

    m.fs.Att2HP = Arc(source=m.fs.ATMP1.outlet,
                      destination=m.fs.turb.inlet_split.inlet)

    m.fs.HPout2RH = Arc(source=m.fs.turb.hp_split[7].outlet_1,
                        destination=m.fs.RH.side_1_inlet)

    m.fs.RHtoIP = Arc(source=m.fs.RH.side_1_outlet,
                      destination=m.fs.turb.ip_stages[1].inlet)

    pyo.TransformationFactory("network.expand_arcs").apply_to(m)

    # unfix boiler connections
    m.fs.ECON.side_1_inlet.flow_mol.unfix()
    m.fs.ECON.side_1_inlet.enth_mol[0].unfix()
    m.fs.ECON.side_1_inlet.pressure[0].unfix()
    m.fs.RH.side_1_inlet.flow_mol.unfix()
    m.fs.RH.side_1_inlet.enth_mol[0].unfix()

source=m.fs.fwh4.cooling.outlet_1, destination=m.fs.fwh3.drain_mix.drain
    )
    m.fs.EXTR_LP4 = Arc(
        source=m.fs.turb.lp_split[4].outlet_2, destination=m.fs.fwh4.desuperheat.inlet_1
    )
    ############################################################################
    #  FWH5 (Deaerator) and boiler feed pump (BFP)                             #
    ############################################################################
    m.fs.FW04 = Arc(
        source=m.fs.fwh4.desuperheat.outlet_2, destination=m.fs.fwh5_da.feedwater
    )
    m.fs.EXTR_IP10 = Arc(
        source=m.fs.turb.ip_split[10].outlet_2, destination=m.fs.fwh5_da.steam
    )
    m.fs.FW05A = Arc(source=m.fs.fwh5_da.outlet, destination=m.fs.bfp.inlet)
    m.fs.EXTR_BFPT_A = Arc(
        source=m.fs.turb.ip_split[10].outlet_3, destination=m.fs.bfpt.inlet
    )
    m.fs.EXHST_BFPT = Arc(source=m.fs.bfpt.outlet, destination=m.fs.condenser_mix.bfpt)
    ############################################################################
    #  High-pressure feedwater heaters                                         #
    ############################################################################
    # fwh6
    m.fs.FW05B = Arc(source=m.fs.bfp.outlet, destination=m.fs.fwh6.cooling.inlet_2)
    m.fs.FWH6_DRN = Arc(
        source=m.fs.fwh6.cooling.outlet_1, destination=m.fs.fwh5_da.drain
    )
    m.fs.EXTR_IP5 = Arc(
        source=m.fs.turb.ip_split[5].outlet_2, destination=m.fs.fwh6.desuperheat.inlet_1
    )
    # fwh7
    m.fs.FW06 = Arc(

# fwh2
    m.fs.FW01B = Arc(
        source=m.fs.fwh1_return.outlet, destination=m.fs.fwh2.cooling.inlet_2
    )
    m.fs.FWH2_DRN = Arc(
        source=m.fs.fwh2.cooling.outlet_1, destination=m.fs.fwh1.drain_mix.drain
    )
    m.fs.EXTR_LP10 = Arc(
        source=m.fs.turb.lp_split[10].outlet_2,
        destination=m.fs.fwh2.desuperheat.inlet_1,
    )
    # fwh3
    m.fs.FW02 = Arc(
        source=m.fs.fwh2.desuperheat.outlet_2, destination=m.fs.fwh3.cooling.inlet_2
    )
    m.fs.FWH3_DRN = Arc(
        source=m.fs.fwh3.cooling.outlet_1, destination=m.fs.fwh2.drain_mix.drain
    )
    m.fs.EXTR_LP8 = Arc(
        source=m.fs.turb.lp_split[8].outlet_2, destination=m.fs.fwh3.desuperheat.inlet_1
    )
    # fwh4
    m.fs.FW03 = Arc(
        source=m.fs.fwh3.desuperheat.outlet_2, destination=m.fs.fwh4.cooling.inlet_2
    )
    m.fs.FWH4_DRN = Arc(
        source=m.fs.fwh4.cooling.outlet_1, destination=m.fs.fwh3.drain_mix.drain
    )
    m.fs.EXTR_LP4 = Arc(
        source=m.fs.turb.lp_split[4].outlet_2, destination=m.fs.fwh4.desuperheat.inlet_1
    )
    ############################################################################

def build_flowsheet():
    m = ConcreteModel()

    m.fs = FlowsheetBlock(default={"dynamic": False})

    m.fs.BT_props = BTXParameterBlock()

    m.fs.M01 = Mixer(default={"property_package": m.fs.BT_props})

    m.fs.H02 = Heater(default={"property_package": m.fs.BT_props})

    m.fs.F03 = Flash(default={"property_package": m.fs.BT_props})

    m.fs.s01 = Arc(source=m.fs.M01.outlet, destination=m.fs.H02.inlet)
    m.fs.s02 = Arc(source=m.fs.H02.outlet, destination=m.fs.F03.inlet)

    TransformationFactory("network.expand_arcs").apply_to(m.fs)

    return m

# Create connections internal to each turbine section (hp, ip, and lp)
        self.hp_stream = Arc(
            self.hp_stream_idx, rule=_arc_rule(self.hp_stages, self.hp_split)
        )
        self.ip_stream = Arc(
            self.ip_stream_idx, rule=_arc_rule(self.ip_stages, self.ip_split)
        )
        self.lp_stream = Arc(
            self.lp_stream_idx, rule=_arc_rule(self.lp_stages, self.lp_split)
        )

        # Connect hp section to ip section unless its a disconnect location
        last_hp = config.num_hp
        if 0 not in config.ip_disconnect and last_hp not in config.hp_disconnect:
            if last_hp in config.hp_split_locations:  # connect splitter to ip
                self.hp_to_ip_stream = Arc(
                    source=self.hp_split[last_hp].outlet_1,
                    destination=self.ip_stages[1].inlet,
                )
            else:  # connect last hp to ip
                self.hp_to_ip_stream = Arc(
                    source=self.hp_stages[last_hp].outlet,
                    destination=self.ip_stages[1].inlet,
                )
        # Connect ip section to lp section unless its a disconnect location
        last_ip = config.num_ip
        if 0 not in config.lp_disconnect and last_ip not in config.ip_disconnect:
            if last_ip in config.ip_split_locations:  # connect splitter to ip
                self.ip_to_lp_stream = Arc(
                    source=self.ip_split[last_ip].outlet_1,
                    destination=self.lp_stages[1].inlet,
                )