class_docstr: Use MLP to fuse different models' features (single-modal and multimodal).
  Specifically, it adapts the features of each model to specified dimensions,
  concatenates the adapted features, and fuses the features through MLP.
code: def label_key(self):
      return f"{self.prefix}_{LABEL}"
  
file_path: autogluon/multimodal/src/autogluon/multimodal/models/fusion/fusion_mlp.py
imports: import logging
  from typing import List, Optional
  import torch
  from torch import nn
  from ...constants import AUTOMM, FEATURES, LABEL, LOGITS, WEIGHT
  from ..mlp import MLP
  from ..utils import init_weights, run_model
  from .base import AbstractMultimodalFusionModel
label_desc: Use image node_id 3 for calling the MultimodalFusionMLP obj's underlying member method code with example usage: obj.label_key() and returns: self, str, LABEL