old_contents: """Defines Header classes and related items"""
  
  # System imports
  import enum
  
  # Third-party imports
  
  # Local source tree imports
  from ofp.v0x01.foundation import base
  from ofp.v0x01.foundation import basic_types
  
  # Enums
  
  
  class OFPType(enum.Enum):
      """Enumeration of Message Types"""
      # Symetric/Immutable messages
      OFPT_HELLO = 0
      OFPT_ERROR = 1
      OFPT_ECHO_REQUEST = 2
      OFPT_ECHO_REPLY = 3
      OFPT_VENDOR = 4
  
      # Switch configuration messages
      # Controller/Switch messages
      OFPT_FEATURES_REQUEST = 5
      OFPT_FEATURES_REPLY = 6
      OFPT_GET_CONFIG_REQUEST = 7
      OFPT_GET_CONFIG_REPLY = 8
      OFPT_SET_CONFIG = 9
  
      # Async messages
      OFPT_PACKET_IN = 10
      OFPT_FLOW_REMOVED = 11
      OFPT_PORT_STATUS = 12
  
      # Controller command messages
      # Controller/switch message
      OFPT_PACKET_OUT = 13
      OFPT_FLOW_MOD = 14
      OFPT_PORT_MOD = 15
  
      # Statistics messages
      # Controller/Switch message
      OFPT_STATS_REQUEST = 16
      OFPT_STATS_REPLY = 17
  
      # Barrier messages
      # Controller/Switch message
      OFPT_BARRIER_REQUEST = 18
      OFPT_BARRIER_REPLY = 19
  
      # Queue Configuration messages
      # Controller/Switch message
      OFPT_QUEUE_GET_CONFIG_REQUEST = 20
      OFPT_QUEUE_GET_CONFIG_REPLY = 21
  
  
  # Classes
  
  
  class OFPHeader(base.GenericStruct):
      """Representation of an OpenFlow message Header
  
          :param ofp_type: Type of  the message
          :param xid:      id of the message
          :param length:   Length of the message, including the header itself
      """
      version = basic_types.UBInt8()
      ofp_type = basic_types.UBInt8()
      length = basic_types.UBInt16()
      xid = basic_types.UBInt32()
  
      def __init__(self,
                   ofp_type, xid, length=None):
          self.version = base.OFP_VERSION
          self.ofp_type = ofp_type
          self.length = length
          self.xid = xid
  
new_contents: """Defines Header classes and related items"""
  
  # System imports
  import enum
  
  # Third-party imports
  
  # Local source tree imports
  from ofp.v0x01.foundation import base
  from ofp.v0x01.foundation import basic_types
  
  # Enums
  
  
  class OFPType(enum.Enum):
      """Enumeration of Message Types"""
      # Symetric/Immutable messages
      OFPT_HELLO = 0
      OFPT_ERROR = 1
      OFPT_ECHO_REQUEST = 2
      OFPT_ECHO_REPLY = 3
      OFPT_VENDOR = 4
  
      # Switch configuration messages
      # Controller/Switch messages
      OFPT_FEATURES_REQUEST = 5
      OFPT_FEATURES_REPLY = 6
      OFPT_GET_CONFIG_REQUEST = 7
      OFPT_GET_CONFIG_REPLY = 8
      OFPT_SET_CONFIG = 9
  
      # Async messages
      OFPT_PACKET_IN = 10
      OFPT_FLOW_REMOVED = 11
      OFPT_PORT_STATUS = 12
  
      # Controller command messages
      # Controller/switch message
      OFPT_PACKET_OUT = 13
      OFPT_FLOW_MOD = 14
      OFPT_PORT_MOD = 15
  
      # Statistics messages
      # Controller/Switch message
      OFPT_STATS_REQUEST = 16
      OFPT_STATS_REPLY = 17
  
      # Barrier messages
      # Controller/Switch message
      OFPT_BARRIER_REQUEST = 18
      OFPT_BARRIER_REPLY = 19
  
      # Queue Configuration messages
      # Controller/Switch message
      OFPT_QUEUE_GET_CONFIG_REQUEST = 20
      OFPT_QUEUE_GET_CONFIG_REPLY = 21
  
  
  # Classes
  
  
  class OFPHeader(base.GenericStruct):
      """Representation of an OpenFlow message Header
  
          :param ofp_type: Type of  the message
          :param xid:      id of the message
          :param length:   Length of the message, including the header itself
      """
      version = basic_types.UBInt8()
      ofp_type = basic_types.UBInt8()
      length = basic_types.UBInt16()
      xid = basic_types.UBInt32()
  
      def __init__(self, ofp_type=None, xid=None, length=None):
          self.version = base.OFP_VERSION
          self.ofp_type = ofp_type
          self.length = length
          self.xid = xid
  
subject: Undo header required init variables