public static bool Equals(NullableBoolean x, NullableBoolean y)
		{
			if (x.HasValue != y.HasValue) //one is null
				return false;
			else if (x.HasValue) //therefor y also HasValue
				return x.Value == y.Value;
			else //both are null
				return true;
		}
		public bool Equals(NullableBoolean x)
		{
			return Equals(this, x);
		}