old_contents: """
  This module contains controller application to manage
  a set of OpenFlow switches
  """
  from ryu.base import app_manager
  from ryu.controller import ofp_event
  from ryu.controller.handler import CONFIG_DISPATCHER, MAIN_DISPATCHER
  from ryu.controller.handler import set_ev_cls
  from ryu.ofproto import ofproto_v1_3 as ofp
  from ryu.ofproto import ofproto_v1_3_parser as parser
  
  from fabric.network import Network
  import fabric.packet as pkt
  import fabric.flows as fl
  
  IDLE_TIMEOUT = 10  #: Timeout for dynamic flows
  DEF_PRI = 0
  LOW_PRI = 1
  HIGH_PRI = 2
  
  
  class NetworkManager(app_manager.RyuApp):
      """
      Core class of this package, NetworkManager is a top-level Ryu application
      def features.reply():
          pass
      def port_status():
          pass
      
      """
  
      OFP_VERSIONS = [ofp.OFP_VERSION]
  
      def __init__(self, *args, **kwargs):
          super(NetworkManager, self).__init__(*args, **kwargs)
          self.net = Network()  #: Init the Network instance
  
      @set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER)
      def _handle_switch_features(self, ev):
          """
          Handle new switches connecting to the network
          """
          pass
  
      @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
      def _handle_packet_in(self, ev):
      
          def packet_in(ev):
              p=pkt.parse(ev.msg.data)
              if p["dl_type"]
              
              ....PASS
          
          def reply_to_arp(dp):
              pass
              
          def send_lldp(dp):
              pass
      
          Handle unknown flow seen on the switches
          
          pass
  
  
  
  
new_contents: """
  This module contains controller application to manage
  a set of OpenFlow switches
  """
  from ryu.base import app_manager
  from ryu.controller import ofp_event
  from ryu.controller.handler import CONFIG_DISPATCHER, MAIN_DISPATCHER
  from ryu.controller.handler import set_ev_cls
  from ryu.ofproto import ofproto_v1_3 as ofp
  from ryu.ofproto import ofproto_v1_3_parser as parser
  
  from fabric.network import Network
  import fabric.packet as pkt
  import fabric.flows as fl
  
  IDLE_TIMEOUT = 10  #: Timeout for dynamic flows
  DEF_PRI = 0
  LOW_PRI = 1
  HIGH_PRI = 2
  
  
  class NetworkManager(app_manager.RyuApp):
      """
      Core class of this package, NetworkManager is a top-level Ryu application
      """
      
      def features.reply():
          pass
      
      def port_status():
          pass
      
      
  
      OFP_VERSIONS = [ofp.OFP_VERSION]
  
      def __init__(self, *args, **kwargs):
          super(NetworkManager, self).__init__(*args, **kwargs)
          self.net = Network()  #: Init the Network instance
  
      @set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER)
      def _handle_switch_features(self, ev):
          """
          Handle new switches connecting to the network
          """
          pass
  
      @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
      def _handle_packet_in(self, ev):
      
          def packet_in(ev):
              p=pkt.parse(ev.msg.data)
              if p["dl_type"]
              
              ....PASS
          
          def reply_to_arp(dp):
              pass
              
          def send_lldp(dp):
              pass
      
          Handle unknown flow seen on the switches
          
          pass
  
  
  
  
subject: Update app.py