code: def add_image(self, img, label):
      #!!! img should be BGR!!!!
      # assert label >= 0
      # assert label > self.last_label
      idx = self.widx
      header = mx.recordio.IRHeader(0, label, idx, 0)
      if isinstance(img, np.ndarray):
          s = mx.recordio.pack_img(
              header, img, quality=100, img_fmt=".jpg"
          )
      else:
          s = mx.recordio.pack(header, img)
      self.writer.write_idx(idx, s)
      self.widx += 1
  
file_path: insightface/reconstruction/jmlr/rec_builder.py
imports: import pickle
  import numpy
  import os
  import os.path
  import glob
  import argparse
  import cv2
  import time
  import datetime
  import pickle
  import sklearn
  import mxnet
  from utils.utils_config import get_config
  from dataset import FaceDataset, Rt26dof
label_desc: Use image node_id 3 for calling the RecBuilder obj's underlying member method code with example usage: obj.add_image(img, label) without return types