code: def tcp_traceflow(packet, timestamp, *, data_link, count=NotImplemented):
      
      if getattr(packet, 'ip', None):
          ip = packet['ip']
      elif getattr(packet, 'ip6', None):
          ip = packet['ip6']
      else:
          return False, None
      tcp = getattr(ip, 'tcp', None)
      if tcp is not None:
          flags = bin(tcp.flags)[2:].zfill(8)
          data = dict(
              protocol=data_link,                                         # data link type from global header
              index=count,                                                # frame number
              frame=packet2dict(packet, timestamp, data_link=data_link),  # extracted packet
              syn=bool(int(flags[6])),                                    # TCP synchronise (SYN) flag
              fin=bool(int(flags[7])),                                    # TCP finish (FIN) flag
              src=ipaddress.ip_address(ip.src),                           # source IP
              dst=ipaddress.ip_address(ip.dst),                           # destination IP
              srcport=tcp.sport,                                          # TCP source port
              dstport=tcp.dport,                                          # TCP destination port
              timestamp=timestamp,                                        # timestamp
          )
          return True, data
      return False, None
docs: Trace packet flow for TCP.