264     _header_length = 40  variable in IPv6Header
354         return self._header_length
480     _header_length = 8  variable in UDPHeader
499         self._payload_length = self._header_length + value
519         return self._header_length
565     _header_length = 4  variable in ICMPv6Header
585         return self._header_length
762     _header_length = 2  variable in HopByHopOptionHeader
778         return self._header_length
817     _header_length = 2  variable in MPLOption
847         return self._header_length + self._seed_id_length[self.S]
1162     _header_length = 4  variable in ICMPv6EchoBody
1183         return self._header_length + len(self.data)
1196     _header_length = 4  variable in ICMPv6DestinationUnreachable
1217         return self._header_length + len(self.data)