code: def test_sample_inputs(self):
      torch.manual_seed(7)
  
      batch = torch.tensor(
          [[[0.1, 0.5, 0.6], [0.8, 0.6, 0.5], [0.2, 0.4, 0.7]]]
      )
      target = torch.tensor([1])
      state = {
          torchbearer.INPUT: batch,
          torchbearer.TARGET: target,
          torchbearer.DEVICE: "cpu",
      }
  
      bcplus = BCPlus(classes=4)
      bcplus.on_sample(state)
  
      lam = torch.ones(1) * 0.2649
  
      self.assertTrue(
          (
              (
                  state[torchbearer.INPUT]
                  * (lam.pow(2) + (1 - lam).pow(2)).sqrt()
              )
              - (batch - batch.mean())
          )
          .abs()
          .le(1e-4)
          .all()
      )
  
file_path: torchbearer/tests/callbacks/test_between_class.py
imports: from unittest import TestCase
  import torch
  import torchbearer
  from torchbearer.callbacks import BCPlus
label_desc: Use image node_id 4 for calling the TestBCPlus obj's underlying member method code with example usage: obj.test_sample_inputs() without return types