public void CountNeighbouringLights()
{
_day18.ParseLights(_sample);
Assert.AreEqual(1, _day18.NumberOfOnNeighbours(0, 0));
Assert.AreEqual(0, _day18.NumberOfOnNeighbours(1, 0));
Assert.AreEqual(3, _day18.NumberOfOnNeighbours(2, 0));
}