old_contents: """Valve Manager base class"""
  
  # pylint: disable=R0201
  # pylint: disable=W0613
  class ValveManagerBase: # pylint: disable=too-few-public-methods
      """Base class for ValveManager objects.
  
      Expected to control the installation of flows into datapath tables.
  
      Ideally each datapath table should be controlled by 1 manager only."""
  
      _MISS_PRIORITY = 0
      _LOW_PRIORITY = 0x1000
      _MATCH_PRIORITY = 0x2000
      _LPM_PRIORITY = 0x3000
      _HIGH_PRIORITY = 0x4000
      _FILTER_PRIORITY = 0x5000
  
      def initialise_tables(self):
          '''initialise tables controlled by this manager'''
          return []
  
      def add_vlan(self, vlan):
          """install flows in response to a new vlan"""
          return []
  
      def add_port(self, port):
          """install flows in response to a new port"""
          return []
  
      def del_vlan(self, vlan):
          """delete flows in response to a vlan removal"""
          return []
  
      def del_port(self, port):
          """delete flows in response to a port removal"""
          return []
  
new_contents: """Valve Manager base class"""
  
  # pylint: disable=R0201
  # pylint: disable=W0613
  class ValveManagerBase: # pylint: disable=too-few-public-methods
      """Base class for ValveManager objects.
  
      Expected to control the installation of flows into datapath tables.
  
      Ideally each datapath table should be controlled by 1 manager only."""
  
      _MISS_PRIORITY = 0
      _LOW_PRIORITY = 0x1000
      _MATCH_PRIORITY = 0x2000
      _LPM_PRIORITY = 0x3000
      _HIGH_PRIORITY = 0x4000
      _FILTER_PRIORITY = 0x5000
  
      def initialise_tables(self):
          """initialise tables controlled by this manager."""
          return []
  
      def add_vlan(self, vlan):
          """install flows in response to a new VLAN"""
          return []
  
      def update_vlan(self, vlan):
          """flows in response to updating an existing VLAN."""
          return []
  
      def add_port(self, port):
          """install flows in response to a new port"""
          return []
  
      def del_vlan(self, vlan):
          """delete flows in response to a VLAN removal"""
          return []
  
      def del_port(self, port):
          """delete flows in response to a port removal"""
          return []
  
subject: Update manager API for update.