/// <summary>
/// Enter the second path.
/// </summary>
/// <param name="type">Type</param>
public void EnterSecond(XType type)
{
ys.Add(type);
}
/// <summary>
/// Enter the first path.
/// </summary>
/// <param name="type">Type</param>
public void EnterFirst(XType type)
{
xs.Add(type);
}