docs: public static String format(Instance inst, String[] labels, String[] gold) {
  
  		StringBuilder sb = new StringBuilder();
  		String[][] data = (String[][]) inst.getSource();
  		int feaNum = data.length;
  		int seqNum = data[0].length;
  		for (int i = 0; i < seqNum; i++) {
  			for (int j = 0; j < feaNum; j++) {
  				sb.append(data[j][i]);
  				sb.append("\t");
  			}
  			sb.append(labels[i]);
  			sb.append("\t");
  			sb.append(gold[i]);
  			sb.append("\n");
  		}
  		return sb.toString();
  	}