class_docstr: Prepare ground-truth labels for the model specified by "prefix".
  For multiple models, we need to create a LabelProcessor for each model so that
  each model will have independent labels.
code: def label_key(self):
      return f"{self.prefix}_{LABEL}"
  
file_path: autogluon/multimodal/src/autogluon/multimodal/data/process_label.py
imports: from typing import Any, Dict, List, Optional, Union
  from torch import nn
  from ..constants import LABEL, MMDET_IMAGE
  from .collator import ListCollator, StackCollator
label_desc: Use image node_id 2 for calling the LabelProcessor obj's underlying member method code with example usage: obj.label_key() and returns: self, str, LABEL