code: func validatePINGRESPBytes(fixedHeader FixedHeader, remaining []byte) error {
  	// Extract the MQTT Control Packet type.
  	ptype, err := fixedHeader.ptype()
  	if err != nil {
  		return err
  	}
  
  	// Check the length of the fixed header.
  	if len(fixedHeader) != lenPINGRESPFixedHeader {
  		return ErrInvalidFixedHeaderLen
  	}
  
  	// Check the MQTT Control Packet type.
  	if ptype != TypePINGRESP {
  		return ErrInvalidPacketType
  	}
  
  	// Check the reserved bits of the fixed header.
  	if fixedHeader[0]<<4 != 0x00 {
  		return ErrInvalidFixedHeader
  	}
  
  	// Check the Remaining Length of the fixed header.
  	if fixedHeader[1] != 0x00 {
  		return ErrInvalidRemainingLength
  	}
  
  	// Check the length of the remaining.
  	if len(remaining) != 0 {
  		return ErrInvalidRemainingLen
  	}
  
  	return nil
  }
docs: // validatePINGRESPBytes validates the fixed header and the remaining.