public static void inversion(Deck in){
	int pos1 = (int) (Math.random() * (1+in.cards.size()));
	int pos2 = (int) (Math.random() * (1+in.cards.size()));
	
	if(pos1>pos2){
	    int temp = pos1;
	    pos1 = pos2;
	    pos2 = temp;
	}
	
	String temp;
	int j = pos2;
	for(int i=pos1; i<(j-1); i++){
	    j--;
	    temp = in.cards.get(i);
	    in.cards.set(i, in.cards.get(j));
	    in.cards.set(j, temp);
	}
    }