class_docstr: A multi-layer perceptron block, based on: "Dosovitskiy et al.,
  An Image is Worth 16x16 Words: Transformers for Image Recognition at Scale <https://arxiv.org/abs/2010.11929>"
code: def forward(self, x):
      x = self.fn(self.linear1(x))
      x = self.drop1(x)
      x = self.linear2(x)
      x = self.drop2(x)
      return x
  
file_path: MONAI/monai/networks/blocks/mlp.py
imports: from __future__ import annotations
  import torch.nn
  from monai.networks.layers import get_act_layer
  from monai.utils import look_up_option
label_desc: Use image node_id 2 for calling the MLPBlock obj's underlying member method code with example usage: obj.forward(x) and returns: x