docs: def _make_pcaps(self):
          '''
          Internal method.  Create libpcap devices
          for every network interface we care about and
          set them in non-blocking mode.
          '''
          self._pcaps = {}
          for devname,intf in self._devinfo.items():
              if intf.iftype == InterfaceType.Loopback:
                  senddev = _RawSocket(devname, protocol=IPProtocol.UDP)
                  self._localsend[devname] = senddev
              pdev = PcapLiveDevice(devname) 
              self._pcaps[devname] = pdev