code: def _read_mptcp_add(self, bits, size, kind):
          
          vers = int(bits, base=2)
          adid = self._read_unpack(1)
          ipad = self._read_fileng(4) if vers == 4 else self._read_fileng(16)
          ip_l = 4 if vers == 4 else 16
          pt_l = size - 1 - ip_l
          port = self._read_unpack(2) if pt_l else None
  
          data = dict(
              kind=kind,
              length=size + 1,
              subtype='ADD_ADDR',
              addaddr=dict(
                  ipver=vers,
                  addrid=adid,
                  addr=ipaddress.ip_address(ipad),
                  port=port,
              ),
          )
  
          return data
docs: Read Add Address option.
  
          Positional arguments:
              * bits - str, 4-bit data
              * size - int, length of option
              * kind - int, 30 (Multipath TCP)
  
          Returns:
              * dict -- extracted Add Address (ADD_ADDR) option
  
          Structure of ADD_ADDR [RFC 6824]:
                                   1                   2                   3
               0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
              +---------------+---------------+-------+-------+---------------+
              |     Kind      |     Length    |Subtype| IPVer |  Address ID   |
              +---------------+---------------+-------+-------+---------------+
              |          Address (IPv4 - 4 octets / IPv6 - 16 octets)         |
              +-------------------------------+-------------------------------+
              |   Port (2 octets, optional)   |
              +-------------------------------+
  
              Octets      Bits        Name                        Description
                0           0     tcp.mp.kind                 Kind (30)
                1           8     tcp.mp.length               Length
                2          16     tcp.mp.subtype              Subtype (3)
                2          20     tcp.mp.addaddr.ipver        IP Version
                3          24     tcp.mp.addaddr.addrid       Address ID
                4          32     tcp.mp.addaddr.addr         IP Address (4/16)
                8-20   64-160     tcp.mp.addaddr.port         Port (optional)