code: def dispatch_hook(cls, s=None, *_args, **_kwds):
          # type: (Optional[str], *Any, **Any) -> base_classes.Packet_metaclass
          
          if s is None:
              return config.conf.raw_layer
          fb = orb(s[0])
          if fb & 0x80 != 0:
              return HPackIndexedHdr
          if fb & 0x40 != 0:
              return HPackLitHdrFldWithIncrIndexing
          if fb & 0x20 != 0:
              return HPackDynamicSizeUpdate
          return HPackLitHdrFldWithoutIndexing
docs: dispatch_hook returns the subclass of HPackHeaders that must be used
          to dissect the string.