public static String toString(int numPrev){
		String retStr = "";
		if (numPrev <= 0 || numPrev > history.size()){ // Prevent index out of range error
			numPrev = 1;
		}
		Object[][] deltaBoard = history.get(history.size() - numPrev);
		retStr += "History #: " + history.size() + "\n";
		for (int y = 0;y < 8;y++) {
			for (int x = 0;x < 8;x++){
				if (deltaBoard[y][x] == null){
					retStr += "_____" + "\t\b";
					continue;
				}
				retStr += " " + deltaBoard[y][x] + "\t\b";
			}
			retStr += "\n";
		}
		return retStr.substring(0,retStr.length()-1); // Remove extra newline
	}