public Zen <Option <SimplePacket> > Forward(int[] path, Zen <SimplePacket> p, Zen <IList <Tuple <int, int> > > failedLinks)
{
Zen <Option <SimplePacket> > x = Some(p);
for (int i = 0; i < path.Length - 1; i++)
{
var currNode = nodes[path[i]];
var nextNode = nodes[path[i + 1]];
// want to use path[i], path[i+1] to check failedLinks to see if link between them is failed. Use this condition to set x
var linkOK = Not(Or(failedLinks.Contains(new Tuple <int, int>(path[i], path[i + 1])), failedLinks.Contains(new Tuple <int, int>(path[i + 1], path[i]))));
x = If(linkOK, x, Null <SimplePacket>());
x = If(x.HasValue(), currNode.ForwardInAndOut(x.Value(), nextNode.Address), x);
}
return(x);
}