Subsets

	/**
	 * Get all subsets of the given set
	 * 
	 * e.g.
	 * 
	 * 		{1, 2, 3}
	 * 
	 * 		{}, {1}, {2}, {3}, {1, 2}, {1, 3}, {2, 3}, {1, 2, 3}
	 * 
	 * */