old_contents: # Copyright (c) 2015 Nicolas JOUANIN
  #
  # See the file license.txt for copying permission.
  from hbmqtt.mqtt.packet import MQTTPacket, MQTTFixedHeader, PacketType
  from hbmqtt.errors import HBMQTTException
  
  class PingReqPacket(MQTTPacket):
      VARIABLE_HEADER = None
      PAYLOAD = None
  
      def __init__(self, fixed: MQTTFixedHeader=None, variable_header=None, payload=None):
          if fixed is None:
              header = MQTTFixedHeader(PacketType.PINGREQ, 0x00)
          else:
              if fixed.packet_type is not PacketType.DISCONNECT:
                  raise HBMQTTException("Invalid fixed packet type %s for PingReqPacket init" % fixed.packet_type)
              header = fixed
          super().__init__(header)
          self.variable_header = None
          self.payload = None
  
new_contents: # Copyright (c) 2015 Nicolas JOUANIN
  #
  # See the file license.txt for copying permission.
  from hbmqtt.mqtt.packet import MQTTPacket, MQTTFixedHeader, PacketType
  from hbmqtt.errors import HBMQTTException
  
  class PingReqPacket(MQTTPacket):
      VARIABLE_HEADER = None
      PAYLOAD = None
  
      def __init__(self, fixed: MQTTFixedHeader=None, variable_header=None, payload=None):
          if fixed is None:
              header = MQTTFixedHeader(PacketType.PINGREQ, 0x00)
          else:
              if fixed.packet_type is not PacketType.PINGREQ:
                  raise HBMQTTException("Invalid fixed packet type %s for PingReqPacket init" % fixed.packet_type)
              header = fixed
          super().__init__(header)
          self.variable_header = None
          self.payload = None
  
subject: Fix typo