code: def remote_ip(local_ip):
      
      local_ip = ip2int(local_ip)
      network = local_ip & pfxlen2mask_int(30)
      return int2ip(network + 3 - (local_ip - network))
docs: Given an IP address, this function calculates the remaining available
      IP address under the assumption that it is a /30 network.
      In other words, given one link net address, this function returns the
      other link net address.
  
      :type  local_ip: string
      :param local_ip: An IP address.
      :rtype:  string
      :return: The other IP address of the link address pair.