text: import torch
  import torch.nn as nn
  import torch.nn.functional as F
  
  
  class ValueNetwork(nn.Module):
      def __init__(self, obs_dim, action_dim, num_vertex, hidden_dim, init_w=3e-3):
          super(ValueNetwork, self).__init__()
  
          self.linear1 = nn.Linear(obs_dim + action_dim + num_vertex, hidden_dim)
          #self.linear1 = nn.Linear(obs_dim + action_dim, hidden_dim)
          self.linear2 = nn.Linear(hidden_dim, hidden_dim)
          self.linear3 = nn.Linear(hidden_dim, 1)
  
          self.linear3.weight.data.uniform_(-init_w, init_w)
          self.linear3.bias.data.uniform_(-init_w, init_w)
  
      def forward(self, state, action, b):
          x = torch.cat((state, action, b), dim=1)
          #x = torch.cat((state, action), dim=1)
          x = F.relu(self.linear1(x))
          x = F.relu(self.linear2(x))
          x = self.linear3(x)
          return x