docs: def zpipe(ctx):
      """build inproc pipe for talking to threads
  
      mimic pipe used in czmq zthread_fork.
  
      Returns a pair of PAIRs connected via inproc
      """
      a = ctx.socket(zmq.PAIR)
      a.linger = 0
      b = ctx.socket(zmq.PAIR)
      b.linger = 0
      socket_set_hwm(a, 1)
      socket_set_hwm(b, 1)
      iface = "inproc://%s" % binascii.hexlify(os.urandom(8))
      a.bind(iface)
      b.connect(iface)
      return a, b