code: def forward(self, x):
      x = self.relu(self.bn0(x))
      x = self.relu(self.bn1(self.conv1(x)))
      x = self.relu(self.bn2(self.conv2(x)))
      x = self.sig(self.conv3(x))
      return x
  
imports: import math
  import torch
  import torch.nn
  from torch.nn.parameter import Parameter
  import torch.nn.functional
label_desc: Use image node_id 2 for calling the Mask obj's underlying member method code with example usage: obj.forward(x) and returns: x