/// <summary>
/// Instantiates a new group from a single stone.
/// </summary>
/// <param name="stone">The stone from which the group is instantiated.</param>
public Group(Stone stone)
{
_stones = new HashSet <Stone>();
_stones.Add(stone);
_player = stone.Player;
}
/// <summary>
/// Returns true if the group contains the stone.
/// </summary>
/// <param name="stone"></param>
/// <returns></returns>
public bool Contains(Stone stone)
{
return(_stones.Contains(stone));
}