docs: def socketpair(family=socket.AF_INET, type=socket.SOCK_STREAM, proto=0):
      """Emulate the Unix socketpair() function on Windows."""
      # We create a connected TCP socket. Note the trick with setblocking(0)
      # that prevents us from having to create a thread.
      lsock = socket.socket(family, type, proto)
      lsock.bind(('localhost', 0))
      lsock.listen(1)
      addr, port = lsock.getsockname()
      csock = socket.socket(family, type, proto)
      csock.setblocking(False)
      try:
          csock.connect((addr, port))
      except socket.error as e:
          if e.errno != errno.WSAEWOULDBLOCK:
              lsock.close()
              csock.close()
              raise
      ssock, _ = lsock.accept()
      csock.setblocking(True)
      lsock.close()
      return (ssock, csock)