old_contents: from experiment_config_lib import ControllerConfig
  from sts.topology import FatTree, MeshTopology, BufferedPatchPanel
  from sts.control_flow import Interactive, Fuzzer
  from sts.input_traces.input_logger import InputLogger
  from sts.invariant_checker import InvariantChecker
  
  # Use POX as our controller
  command_line = "./pox.py --verbose --no-cli openflow.of_01 --address=__address__ --port=__port__ sts.syncproto.pox_syncer samples.topo forwarding.l2_multi messenger.messenger samples.nommessenger"
  controllers = [ControllerConfig(command_line, cwd="pox", sync="tcp:localhost:18899")]
  
  topology_class = MeshTopology
  topology_params = "num_switches=2"
  patch_panel_class = BufferedPatchPanel
  control_flow = Fuzzer(check_interval=1, halt_on_violation=True,
          input_logger=InputLogger(),
          invariant_check=InvariantChecker.check_liveness,
          switch_init_sleep_seconds=2.0)
  dataplane_trace = "dataplane_traces/ping_pong_same_subnet.trace"
  
new_contents: from experiment_config_lib import ControllerConfig
  from sts.topology import FatTree, MeshTopology, BufferedPatchPanel
  from sts.control_flow import Interactive, Fuzzer
  from sts.input_traces.input_logger import InputLogger
  from sts.invariant_checker import InvariantChecker
  
  # Use POX as our controller
  command_line = "./pox.py --verbose --no-cli openflow.of_01 --address=__address__ --port=__port__ sts.syncproto.pox_syncer samples.topo forwarding.l2_multi messenger.messenger samples.nommessenger"
  controllers = [ControllerConfig(command_line, cwd="pox", sync="tcp:localhost:18899")]
  
  topology_class = MeshTopology
  topology_params = "num_switches=2"
  patch_panel_class = BufferedPatchPanel
  control_flow = Fuzzer(check_interval=1, halt_on_violation=True,
                        input_logger=InputLogger(),
                        invariant_check=InvariantChecker.check_liveness,
                        switch_init_sleep_seconds=2.0)
  dataplane_trace = "dataplane_traces/ping_pong_same_subnet.trace"
  
subject: Add liveness check to fuzz_pox_mesh.py