code: def build_model(self):
      self.layers = nn.ModuleList()
      # input to hidden
      i2h = self.build_input_layer()
      self.layers.append(i2h)
      # hidden to hidden
      for _ in range(self.num_hidden_layers):
          h2h = self.build_hidden_layer()
          self.layers.append(h2h)
      # hidden to output
      h2o = self.build_output_layer()
      self.layers.append(h2o)
  
imports: import os
  from functools import partial
  import dgl
  import dgl.function
  import torch
  import torch.nn
  import torch.nn.functional
  from dgl import DGLGraph
label_desc: Use image node_id 2 for calling the Model obj's underlying member method code with example usage: obj.build_model() without return types