class_docstr: Prepare numerical data for the model specified by "prefix".
  For multiple models requiring numerical data, we need to create a NumericalProcessor
  for each related model so that they will have independent input.
code: def numerical_key(self):
      return f"{self.prefix}_{NUMERICAL}"
  
file_path: autogluon/multimodal/src/autogluon/multimodal/data/process_numerical.py
imports: from typing import Any, Dict, List, Optional, Union
  import numpy
  from torch import nn
  from ..constants import COLUMN, NUMERICAL
  from .collator import StackCollator
label_desc: Use image node_id 2 for calling the NumericalProcessor obj's underlying member method code with example usage: obj.numerical_key() and returns: self, str, NUMERICAL