class_docstr: Support MMDET object detection models.
  Refer to https://github.com/open-mmlab/mmdetection
code: def image_valid_num_key(self):
      return f"{self.prefix}_{IMAGE_VALID_NUM}"
  
imports: import logging
  import os
  import time
  import warnings
  from typing import Optional
  import torch
  from torch import nn
  from ..constants import BBOX, BBOX_FORMATS, COLUMN, IMAGE, IMAGE_VALID_NUM, LABEL, XYXY
  from .utils import freeze_model_layers, lookup_mmdet_config, update_mmdet_config
label_desc: Use image node_id 12 for calling the MMDetAutoModelForObjectDetection obj's underlying member method code with example usage: obj.image_valid_num_key() and returns: self, str, IMAGE_VALID_NUM