code: def forward(self, x):
      x = x.view(x.size(0), -1)
      x = self.layer_1(x)
      x = F.relu(x)
      x = self.layer_2(x)
      return x
  
imports: import pytest
  import pytorch_lightning
  import torch
  import torch.nn
  import torch.nn.functional
  from sklearn.datasets import load_diabetes
  from torch.utils.data import Dataset
  from torchvision import transforms
  from torchvision.datasets import MNIST
  import nni
  import nni.nas.evaluator.pytorch.lightning
  from nni.nas.evaluator import FunctionalEvaluator, Evaluator
  from nni.nas.space import RawFormatModelSpace
label_desc: Use image node_id 2 for calling the MNISTModel obj's underlying member method code with example usage: obj.forward(x) and returns: x