public IGrid<Cell> On(IGrid<Cell> grid, Cell startAt = null)
{
if (startAt == null)
{
startAt = grid.RandomCell();
}
var stack = new Stack<Cell>();
stack.Push(startAt);
while (stack.Count != 0)
{
var current = stack.Peek();
var neighbours = current.Neighbours().Where(n => n.Links.Count == 0).ToList();
if (neighbours.Count == 0)
{
stack.Pop();
}
else
{
var neighbour = neighbours[rand.Next(neighbours.Count)];
current.Link(neighbour);
stack.Push(neighbour);
}
}
return grid;
}