docs: def sr(x, promisc=None, filter=None, iface=None, nofilter=0, *args, **kargs):
      """Send and receive packets at layer 3"""
      s = conf.L3socket(promisc=promisc, filter=filter,
                        iface=iface, nofilter=nofilter)
      result = sndrcv(s, x, *args, **kargs)
      s.close()
      return result