code: def test_depth_0(self):
      mm = ManifoldMixup().at_depth(0)
      state = {torchbearer.MODEL: self.model}
      mm.on_start(state)
  
      checks = [
          self.model.fc1 in mm._layers,
          self.model.conv1 in mm._layers,
          self.model.relu in mm._layers,
          self.model.layer1 in mm._layers,
          self.model.layer2 in mm._layers,
      ]
  
      self.assertTrue(all(checks))  # Top level modules in
      self.assertFalse(self.model.layer1.conv in mm._layers)
  
imports: from unittest import TestCase
  from mock import patch, Mock
  from torch import nn
  from torchbearer.callbacks.manifold_mixup import ManifoldMixup
  import torchbearer
  import torch
label_desc: Use image node_id 3 for calling the TestManifoldMixup obj's underlying member method code with example usage: obj.test_depth_0() without return types