code: def forward(self, inputs, **kwargs):
      hidden_rep1 = self.hidden_layer1(inputs, **kwargs)
      hidden_rep2 = self.hidden_layer2(hidden_rep1, **kwargs)
      output = self.last_layer(
          hidden_rep2, expand_for_quadgrid=False, **kwargs
      )
      return output
  
imports: import unittest
  import torch
  import gpytorch
  from gpytorch.kernels import MaternKernel, ScaleKernel
  from gpytorch.likelihoods import GaussianLikelihood
  from gpytorch.means import ConstantMean, LinearMean
  from gpytorch.models.deep_gps.dspp import DSPP, DSPPLayer
  from gpytorch.test.base_test_case import BaseTestCase
  from gpytorch.variational import MeanFieldVariationalDistribution, VariationalStrategy
label_desc: Use image node_id 2 for calling the ThreeLayerDSPP obj's underlying member method code with example usage: obj.forward(inputs) and returns: output